The five minute chunk

Have you noticed how everyone tends to divide time into five minute chunks? No? When someone asks you how long it will take to, say, walk from the station to your office, or any other walk you're familiar with, what do you tell them? Ten minutes? Fifteen? What if it's a walk you do every day, and you *know* it takes almost exactly 12 minutes?

You don't say "12 minutes" do you? Because no-one is that precise. If you did, they'd look at you all peculiar and say something like "give or take 22 seconds." They wouldn't say it, but they'd definitely imply you were being a bit anal, or at least overly analytical, just for knowing the exact time it takes to walk a walk you're intimately acquainted with. No, you don't say 12 minutes. You might think "well hey, I walk a bit slow, so he might do it in ten, or he might hit a bad run of traffic lights and not be able to cross, so it might be 13 or 14" and so you round up. You don't want him to rely on an underestimate and end up being late. You tell him it's a fifteen minute walk. If you want to bracket it, you'll do this in five minute chunks too. "It's about a fifteen minute walk, twenty tops."

It's nothing like twenty minutes! If he was recovering from a broken ankle he could do it in 16. But those minutes between 15 and 20 are lost to you. Too precise.

I really should stop thinking about this stuff.