TV volume settings

This post is based on a tweet. Perhaps this’ll happen more often. I find something pithy to mention and then I’ll expand upon it in a blog post.
My wife was changing the TV volume the other day and making sure she could see the number it was set on (the amp is perpendicular to where we sit, so quite hard to read). I asked whether she was being fussy about what volume the amp was on. No, was the reply, you are the fussy one.
This is correct as I would prefer the TV volume (actually the amp volume) on either a multiple of 2 or 5. Given that for normal TV viewing the ideal volume is somewhere between 20 and 30 this gives plenty of choice: 22,24,25,26,28. The other volume settings are incorrect to use and even if they create the best listening conditions I would find it hard to settle on one of those.
I do not consider this to be weird behaviour, I consider it to be remarkably sensible although I would probably end up with many logical fallacies should I attempt to explain how this obsessiveness can be  justified.
A friend will only get out of bed if, when he looks at the alarm clock, it is a multiple of 5 minutes. If not he will stay in bed until the next multiple. Now that’s weird!