The 1-3-5 Rule: A Simple Framework for Daily Productivity

Why Your 47-Item To-Do List Is Sabotaging Your Productivity

You start Monday with ambition. Twenty-three tasks lined up. By Tuesday afternoon, you’ve ticked off five and added seventeen more.

Sound familiar?

The longer your to-do list grows, the heavier it feels. Decision fatigue sets in. You don’t know where to start, so you tackle the easiest tasks first—answering emails, organising files, anything to feel productive.

Meanwhile, the important work sits untouched.

Here’s the uncomfortable truth: traditional to-do lists don’t force prioritisation. They let everything feel equally urgent, which means nothing actually is.

The 1-3-5 rule fixes this. It’s absurdly simple: each day, you commit to completing one big task, three medium tasks, and five small tasks. Nine items total. That’s it.

No more drowning in endless lists. No more pretending you’ll finish thirty things. Just nine carefully chosen tasks that actually move your work forward.

What Is the 1-3-5 Rule?

The 1-3-5 rule is a task management framework that structures your daily workload into three categories:

1 Big Task: Your most important, impactful work for the day. This is the task that, if completed, makes the entire day feel successful. It requires significant mental energy and time—think writing a crucial report, finalising a project proposal, or having that difficult conversation you’ve been avoiding.

The big task is your Everest. It’s challenging, possibly intimidating, but completing it creates real progress towards your goals.

3 Medium Tasks: Important work that keeps projects moving forward but doesn’t require the same intensity as your big task. These might include client meetings, reviewing documents, planning next week’s priorities, or working through a specific project phase.

Medium tasks are substantial enough to matter but manageable enough to complete alongside your big task.

5 Small Tasks: Quick wins that clear your mental plate. Replying to specific emails, updating a spreadsheet, scheduling appointments, ordering supplies, or making that phone call you’ve been postponing.

Small tasks take 5-15 minutes each. Individually they’re minor, but collectively they prevent the build-up of annoying little jobs that clutter your mind.

Total: Nine tasks. No more, no less (unless you finish early and genuinely have capacity for more).

Why the 1-3-5 Rule Actually Works (The Psychology)

This isn’t just another productivity hack. The 1-3-5 rule aligns with how your brain actually functions.

1. It Respects Your Working Memory Limits

Research by psychologist George Miller found that our working memory can effectively handle 7±2 items at a time. By capping your daily list at nine tasks, you’re working within your brain’s natural processing capacity.

When you try to juggle twenty tasks simultaneously, you’re overwhelming your cognitive resources. The 1-3-5 framework keeps you focused instead of scattered.

2. It Reduces Decision Fatigue

Every decision depletes your mental energy—even tiny ones like “what should I work on next?” By pre-deciding your nine tasks at the start of the day, you eliminate hundreds of micro-decisions.

You simply work through your list. No constant questioning, no second-guessing, no mental energy wasted on task selection. Similar to how batching emails reduces context-switching, the 1-3-5 rule reduces decision-making overhead.

3. It Tackles the Planning Fallacy

We’re terrible at estimating how long tasks take. The planning fallacy describes our tendency to underestimate time requirements—often by 50% or more.

Traditional to-do lists enable this delusion. You list thirty tasks and genuinely believe you’ll complete them all. The 1-3-5 rule forces realism. Nine tasks in a day? That’s actually achievable.

4. It Creates Genuine Progress (The Small Wins Effect)

Harvard research published in the Harvard Business Review found that making progress in meaningful work is the single most important motivator in a professional’s day.

The 1-3-5 rule provides multiple opportunities for progress. You complete your big task—massive win. You tick off medium tasks—solid progress. You clear small tasks—satisfying completion.

Each checkmark triggers your brain’s reward system, building momentum throughout the day.

How to Implement the 1-3-5 Rule (Step-by-Step)

Step 1: Brain Dump Everything

Start with a complete brain dump. Write down every task you can think of—no filtering, no judgment. Big projects, tiny errands, work obligations, personal commitments. Everything.

The goal is to get it all out of your head and onto paper or screen. Don’t worry about organisation yet.

Easy: Spend 5 minutes listing tasks

Set a timer and write continuously. Aim for 15-20 items minimum to ensure you’ve captured everything.

Medium: Categorise as you dump

Create three columns (Big/Medium/Small) and sort tasks as you write them. Saves time in the next step.

Advanced: Include both work and personal tasks

Create separate 1-3-5 lists for work and life, or combine them if your boundaries blur.

Step 2: Size Your Tasks Accurately

Review your list and categorise each item as Big, Medium, or Small based on time and mental energy required.

Big tasks typically take 2-4 hours of focused work. They’re cognitively demanding and high-impact.

Medium tasks take 30-90 minutes. They’re important but less draining than big tasks.

Small tasks take 5-15 minutes. They’re quick wins that clear mental clutter.

Here’s the crucial bit: be honest about task size. Many people underestimate, turning what should be a big task into a medium one, then wonder why their schedule falls apart.

Easy: Use time estimates

If you think it’ll take more than 90 minutes, it’s a big task. Between 30-90 minutes? Medium. Under 30 minutes? Small.

Medium: Track actual durations

For one week, time how long tasks really take. Use this data to size future tasks more accurately.

Advanced: Account for energy, not just time

A 30-minute task requiring intense creative thinking might actually be “medium” due to mental load. Factor in cognitive demand.

Step 3: Select Your Daily Nine

Now choose your 1-3-5 for tomorrow (or today if you’re doing this in the morning).

Choose your one big task by asking: “Which task, if completed, would make tomorrow feel successful?” This should directly advance your most important project or goal.

Select three medium tasks that keep momentum on active projects. Avoid picking three unrelated tasks—better to have three tasks from the same project to reduce context-switching.

Pick five small tasks that need doing but don’t require heavy thinking. These are your “between big work” tasks or energy slump tasks.

Easy: Choose tasks the night before

Spend 10 minutes each evening selecting tomorrow’s nine. You’ll wake up knowing exactly what needs doing.

Medium: Align with weekly goals

At the start of each week, identify 2-3 major goals. Each day’s big task should advance one of these goals.

Advanced: Theme your days

Monday for planning and admin, Tuesday-Wednesday for deep work big tasks, Thursday for meetings and collaboration, Friday for completion and review.

Step 4: Schedule Strategically

Don’t just list your nine tasks—schedule them based on your energy rhythms.

Big task first (usually): Most people experience peak cognitive function mid-morning. Schedule your big task when you’re sharpest. For most, this means tackling it first thing.

Medium tasks next: After completing your big task, you’ll have momentum. Use this to power through medium tasks before your energy dips.

Small tasks fill the gaps: Use small tasks during natural energy slumps (post-lunch, late afternoon) or as transitions between bigger work.

Building on principles of deep work, protect your peak hours for big tasks and relegate shallow work to low-energy periods.

Easy: Start with your big task

Simply do it first, before emails, before meetings, before anything else can derail you.

Medium: Block time for each category

Big task: 9:00-11:30. Medium tasks: 13:00-16:00. Small tasks: 16:00-17:00. Adjust to your natural rhythms.

Advanced: Build buffer time

Add 15-minute gaps between tasks. If something runs over, you won’t immediately fall behind.

Step 5: Focus and Execute

This is where most systems fail: execution. Having a perfect list means nothing if you don’t actually work through it.

Focus on one task at a time. Not two. Not “multitasking.” One. Complete it. Move to the next.

Resist new tasks. When something urgent appears (and it will), ask: “Is this genuinely more important than my big task?” Usually, it isn’t. Capture it for tomorrow’s list.

Adjust when necessary. If your boss needs something immediately, that’s fine. Slide a task to tomorrow. The 1-3-5 rule is flexible—it’s not a rigid prison.

Easy: Use the “capture and delay” technique

New task appears? Write it down immediately, then return to your current work. Schedule it later.

Medium: Batch similar small tasks

Do all five small tasks in one session rather than scattering them throughout the day.

Advanced: Track completion rates

Note which tasks you consistently finish and which you don’t. Patterns reveal whether you’re sizing tasks accurately.

Common Mistakes (And How to Avoid Them)

Mistake 1: Misjudging Task Sizes

You label a task “medium” when it’s actually “big.” By 11am, you’ve spent three hours on one “medium” task and your entire schedule collapses.

Fix: When unsure, size up. Better to finish a “big” task quickly and feel accomplished than struggle with an under-sized task and feel defeated.

Mistake 2: Choosing Unrelated Tasks

Your three medium tasks are: prepare presentation, review budget, plan team event. Three completely different mental contexts.

Fix: Cluster related tasks when possible. Three medium tasks on the same project reduces context-switching fatigue.

Mistake 3: Ignoring Energy Rhythms

You schedule your big task for 3pm when you’re already mentally tired. It takes twice as long and feels frustrating.

Fix: Protect your biological prime time for big tasks. Schedule medium and small tasks for lower-energy periods.

Mistake 4: Being Too Rigid

An emergency arises. Instead of adapting, you abandon the system entirely because your plan “failed.”

Fix: View your nine tasks as a framework, not a contract. Adjust when life demands it, then return to the structure.

Mistake 5: Not Celebrating Completion

You finish your nine tasks, immediately create tomorrow’s list, and never acknowledge what you’ve accomplished.

Fix: Take 30 seconds to appreciate finishing your list. This small recognition reinforces the behaviour and maintains motivation.

Adapting the 1-3-5 Rule to Your Life

The framework is flexible. Modify it to fit your reality:

Reactive roles: If you handle customer service or urgent requests, consider a 1-2-4 approach (fewer medium tasks) or protect just 2-3 hours for your structured nine tasks, leaving the rest for reactive work.

Creative work: Some days require deep, unstructured thinking. On those days, use 1-0-3 (one big creative task, zero medium, three admin tasks).

Low-energy days: Feeling ill or exhausted? Try 0-2-5 (skip the big task, focus on medium and small to maintain momentum without overwhelming yourself).

High-small-task days: Sometimes you genuinely have twelve quick tasks. Adapt to 1-1-10 (one big, one medium, ten small).

The ratio isn’t sacred. The principle is: prioritise intentionally, limit your commitments, and focus on completion over endless listing.

Your Next Steps

The 1-3-5 rule isn’t magic. It’s simply structure that forces honest prioritisation.

For tomorrow, try this: tonight, select one big task, three medium tasks, and five small tasks. Write them down. Not thirty tasks. Just nine.

Tomorrow morning, start with your big task. Before emails. Before Slack. Before anything else.

Complete it. Then move to your medium tasks. Then your small tasks.

By tomorrow evening, you’ll have finished nine meaningful tasks instead of half-completing twenty unimportant ones. That’s the difference between busy and productive.

The goal isn’t a perfect system. The goal is finishing what matters—with enough flexibility to handle reality when it inevitably happens. Just like the 2-minute rule uses tiny actions to overcome inertia, the 1-3-5 rule uses limited choices to overcome overwhelm.

Simon Shaw is a Chartered Occupational Psychologist with over 20 years of experience optimising workplace performance and mental productivity. He specialises in translating cognitive psychology research into practical frameworks that help professionals work smarter, not harder.