It just occured to me that for all time increments up to and including 1 minute 39 seconds, you save one button-push if you enter it as seconds (99). On the other hand, you might lose that time in mentally converting from, say, 1 minute 15 seconds to 75 seconds.
Also, I’ve been at work for 12 hours now. Or 720 minutes, or 43,200 seconds. And am in no danger of leaving any time soon.
Mundane and pointless; I think that fits the bill.
This drove my coworkers crazy. And I still do it.
44 second, 55 seconds, 66, 77, 88, 99, 1:11, 1:22, 1:33…all the way to 1:99, then 2:22, 2:33, 2:44 all the way to 2:99, then 3:33 on up…and so on and so on…
My defense?
Have you actually calibrated exactly how much time it takes to cook/heat up object X ?
I am lazy.
And yeah, I realize that sequence aint perfectly sequential
My microwave (and the one at work) just has a dial that you turn (marked with dots and numbers that appear to bear no relation whatsoever to the amount of time it will run).
So I just tend to turn it to about 5 minutes and then stand there looking at my watch.
Bah.
MINUTE PLUS is your friend!
One-click microwaving versus three for your method 
Uh. If you just want to heat up 1/8 cups of water, that is. Otherwise, maybe two. Or five. Nevermind.
I used to do this. Now our microwave has an “add minute” button and immediately starts. It also has “less” and “more” buttons that subtract or add 10 seconds each press. It may take me four presses to get 30 or 90 seconds, but it’s running after the first press, which is what matters to me. I think there’s also an “add 5 minutes” button, but I never need it.
Mine has “quick start” on buttons 1-6, which will start instantly upon a single push for one to six minutes. If you want something oddball, like exactly 99 seconds, you’ll need to push “Time Cook”, then enter the time, then push Start. Way too many presses.
I do love the “Add :30” button. Just push the 3, then “Add :30”, and BAM, you got three minutes and thirty seconds of cooking, brother.