On a typical work calendar, meetings are spread across the day and the free time between them comes in pieces of twenty or thirty minutes. Most of us plan to do our hardest work in those pieces. By evening the meetings have happened and the hard work mostly hasn’t.
Short gaps are a poor fit for demanding work because of how long it takes to get started. Before you can make progress on a difficult problem, you have to remember what you were trying to do, what you already tried and where you got stuck. For many people that takes ten to fifteen minutes. In a twenty-minute gap, that leaves five minutes of actual work.
Switching has a cost
Researchers who study task switching describe something called attention residue: after you move from one task to another, some of your attention stays on the first one for a while, especially if you left it unfinished. A meeting that ended on an open question will still be on your mind when you sit down to write.
Longer blocks don’t remove this cost, but they make it a small share of the time. Fifteen minutes of warm-up in a 90-minute block still leaves more than an hour of focused work.
How long a block should be
For most people, somewhere between 60 and 120 minutes works well. Ninety minutes is a reasonable place to start because it fits into a morning or an afternoon without taking all of it.
Adjust from there. If you notice your attention drifting after about 50 minutes, try 60-minute blocks for a while. If you often look up and find two hours have passed, you can go longer.
How many blocks a day
Fewer than you might expect. Studies of skilled performers, including musicians and writers, often find that people sustain about three to four hours of their most demanding practice a day before the quality drops.
For most office jobs, one or two blocks a day is a good target. Two 90-minute blocks on a hard project will usually move it further than a full day of work done in fragments.
Protecting the blocks
A block only survives if it is on the calendar before other people fill the week. Some practical rules:
- Book blocks before the week starts. On Friday or Sunday, add next week’s blocks to your calendar as events. A short weekly review is a good moment to do it.
- Use the same time every day. A fixed slot such as 9:00 to 10:30 means one less decision each morning, and colleagues learn when you’re unavailable.
- Write down the task, not just the time. “Draft section 2 of the proposal” is easier to start than an event called “Deep work”.
- Remove interruptions at the start. Close email and chat, and put your phone in another room.
- Stop five minutes early. Write a note about where you stopped and what comes next, so tomorrow’s warm-up is shorter.
Using the gaps
The short gaps are still useful for work that doesn’t need a long run-up: replying to messages, reviewing a document, filing expenses, planning the next day. Grouping those small tasks into fixed times works even better; see Put Your Inbox on a Schedule. Once you stop expecting them to hold your hardest work, they become easier to use well.
A one-week test
Pick one project that matters and book three 90-minute blocks for it next week, at the same time each day. Treat them like meetings with someone else. At the end of the week, compare how far the project moved with a normal week.