In my place of work the bathrooms technically have low flow toilets, but they are flushometer (not tank) toilets and the flush on them is prodigious and is capable of sucking down a medium size dog. I still occasionally find myself sitting next to someone who will flush as many as 6 times in as many minutes. I have always attributed this to some sort of OCD behavior. Once, in my youth, I asked someone about this; “Hey Spanky, what’s with all the flushes?” (it was during a drought and I was a wise ass kid, so it might have appeared confrontational). After telling me to fuck off, he rattled on about “courtesy flushes”. I have gotten older and less able to defend myself, so I keep my own counsel in the bathroom.
There are also many people who flush before they sit down, lest any filth (or snakes) be lurking in the depths below. I have a friend who engages in this behavior and when I asked him about it, he said “I like a clean bowl”. I remember reading about a pair of identical twins separated at birth who, when they were reunited late in life, discovered that habit as one of the things they shared. So I gather it is a genetic tendency.
I think our shit is like our children; we like having them, but we don’t want them to hang around too long.