Yes ^ All of that!! I'm the same way.

Those are very comfortable numbers and easy to organize.

And I too have to do certain things a certain number of times. Often I stop with 3, but I am so much more relieved with 4. So I might do things 3 times in a row, then stop and I might do it just one more time for extra assurance, so it equals to 4. If I ever have to check on something a 5th time, I sometimes get confused and would have to start over again (even though multiples of 5 are good for larger numbers and counting related projects, 5 on it's own is out of the ordinary for me for checks and such)

I try my best not to think about it too much, but sometimes the 3/4 rule is a good allowance - it may sorta suck to give oneself a rule like that, that you "have to do this __ times"... but that ridiculous little rule is usually better than just doing something or checking something over and over again nonstop with no end in sight.