Everything you do takes two kinds of time: active time and “dead” time.
Let’s say you have an eight-hour workday. It starts at 9 and ends at 5, Monday through Friday. So you have a 40-hour workweek, right?
No way. You have to commute. You have to arrive early enough to be settled in and ready to work at 9, not walking in the door at 9. You have to get ready to commute. You might have to change when you get home. All told, from the moment you have to start doing work-related things to the moment you stop, you might be looking at 50 hours a week, 60, 70.
This isn’t me railing against the modern work week or anything. It’s just an example of how nothing actually takes only the time it takes. You might be working on a task and someone says “Hey, can I interrupt you for a minute and have you handle this very simple task? It’ll take 2 minutes.” They might be correct in that the task itself is a 2-minute task. But the total disruption to what you’re doing could be way longer. First, you have to stop what you’re doing, losing momentum and having to regain your place later. The other person has to explain the request. You have to get to where you can do it – maybe it’s physically in another location, maybe you have to open different programs, maybe you have to retrieve a different tool or find different info. Then you do the task – boom, 2 minutes, great – and then you do all of that in reverse to get back to what you were doing originally.
This is why blocks of related work time are valuable – the “dead time” tends to be clustered around the start and finish, so if you have fewer starts and fewer finishes you have less dead time. (Incidentally, that’s why I always preferred a four-day workweek of 10-hour days as opposed to an 5/8 setup when I worked hourly. If you manage hourly employees, try it.)
The reason this is relevant is because dead time adds up. Especially if you do a lot of smaller, unrelated tasks as opposed to big blocks of uninterrupted things, the dead time can really kill productivity and efficiency if not managed – or at least expected.
Consider: you have 10 tasks to do, and you (accurately!) predict that each of them alone will take 30 minutes. So you end up assuming you’ve got 5 hours of work ahead of you, but it ends up taking twice that and you end up very frustrated, behind schedule, or failing. That’s the dead time – those 10- and 15-minute transitions barely seem like enough to consider during the planning stage, but they add up very quickly when you have a lot of them.
And also, like, people go to the bathroom. They eat. They stretch their legs. Those are pretty important.
When you’re planning your own tasks (and especially other people’s!), make sure you’re giving ample allowance for dead time. It’s fine to try to cut down on it – if there’s 45 minutes of dead time on either side of every 10-minute task, that’s a problem – but you can’t ever really eliminate it and you’ll be frustrated and stressed forever if you try.