The Time Trap: Why “Five Minutes” Always Takes 20
You’ve been there before: promising to finish that report by Thursday, assuring your spouse you’ll be ready in “just five minutes,” or confidently scheduling back-to-back meetings with zero buffer time. Then reality hits, deadlines whoosh by, and you’re left wondering why you’re so bad at estimating time.
You’re not alone, and you’re not simply bad at planning. Most people tend to systematically underestimate the time, costs, and risks of future actions while overestimating their benefits. This is the “planning fallacy,” first described by psychologists Daniel Kahneman and Amos Tversky.
The Psychology Behind Our Time Blindness
The planning fallacy is more than just poor time management. Imagine you are short on time but really have to write an email to a colleague. You quickly estimate that it will not take too long, so you sit down and start typing. Alas, it takes far longer than you thought, and now you are hopelessly late. What has happened?
Most likely, you visualized yourself typing the message, perhaps reviewing it once, and hitting send. The problem is that, when you plan, you zoom in on the task itself while ignoring the countless small disruptions, interruptions, and complications that inevitably arise while you are trying to finish it. So you don’t account for the three other urgent emails that will arrive while you are writing your message, or the need to look up some specific figures you need to reference.
The planning fallacy also explains why large projects, from house renovations to software launches or construction projects, consistently run over budget and behind schedule. The Sydney Opera House was supposed to be finished in 1963 and cost $7 million. It was completed in 1973 at $102 million. Berlin’s new airport was supposed to open in 2011 with a budget of 2 billion euros. It opened in 2020 and cost over 6 billion euros. And so on.
Part of the reason is that each person involved makes optimistic estimates, which are factored in by others and quickly multiply to yield wildly unrealistic expectations. The problem is often compounded by the sunk cost fallacy, by which we refuse to accept failure when costs escalate and delays accumulate, and throw more time and money at the project instead.
How to Avoid the Planning Fallacy
The planning fallacy can be very costly—and it can cost more than just money. Missed deadlines damage your reputation and make your colleagues, clients, and significant others lose trust in you. Poor planning eats your time and resources away, and other opportunities will pass you by. And when every task takes longer than expected, you will be constantly playing catch-up, which will create unnecessary stress and might have health consequences.
What can you do? Here are some strategies, based on research in psychology and management, that can help you.
1. Learn about yourself.
Instead of thinking about the task, use data. Daniel Kahneman and Dan Lovallo distinguished between the “inside view” (focusing on the specific, current task) and the “outside view” (looking at what happened in similar cases), and recommended using the outside view for better predictions. How long do you think that others take to complete similar tasks? Why do you think you will be faster?
Think back to when you last completed a similar task. How long did it take? This works best if you keep some actual notes (a simple notebook will do, but use a spreadsheet if you like). For example, before estimating how much time you need to prepare your next presentation, review your notes from the last three presentations. Be sure to count not just the writing time, but the research, revisions, and formatting.
2. Add buffers as percentages.
Adding buffers is a good idea, but “a little extra time” will never be enough. Research in psychology shows that people systematically underestimate task duration by substantial margins.
One rule of thumb to keep you realistic is to add percentages instead of fixed time buffers. Add 25 percent to your estimate (instead of 10 minutes more). If you still end up needing more, add 50 percent next time. If you are left with extra time, adjust it down a bit next time. Don’t be depressed if you end up adding 150 percent or more. We are really that bad at estimating duration.
3. Break tasks into steps.
Estimates for large, complex tasks are particularly prone to the planning fallacy because they involve many unknowns. Break big projects into smaller, more predictable steps, and estimate the duration of each one. It’s easier to estimate “get the sales data from last quarter” than “complete the division’s report.”
4. Plan backwards.
Start with the actual deadline and work backwards, step by step, using estimates from previous tasks and buffers. Schedule the actual work in your calendar. Then add more time to avoid stress. Do you really want to be finishing the task at the last possible minute?
5. Use implementation intentions.
Vague commitments and well-intended goals rarely work. Instead, create specific if-then plans for each task: “If it’s 9 AM on Tuesday, then I’ll spend 30 minutes outlining the proposal.” “Once I have the sales data, I will create the graphs for the quarter.” Psychologists Peter Gollwitzer and Anja Achtziger, among others, have shown that this simple trick is surprisingly powerful.
The Benefits of Realistic Planning
When you learn to make more accurate time estimates, you will experience less stress, deliver higher-quality work, and improve your reputation for reliability. Paradoxically, you will also save time. If each task is consistently completed in time, you will never be overwhelmed. You will reclaim the mental space needed for creative work and will have the time to pursue other opportunities.
The next time you catch yourself thinking “this will just take a few minutes,” pause and remember the planning fallacy. The goal, however, is not to become pessimistic about your capabilities. It’s to become realistic about the complexities of the real world. Your future self will thank you.