Right-sizing Proclivity?

When I was a kid, after big parties at the house, there'd be a load of leftovers to fit into the fridge.  I found that I really enjoyed this activity, specifically, looking at the bowl of food, finding the smallest tupperware that would fit the food, then arranging the items in the fridge in just the right way as to maximize volume usage.  It was rather satisfying to do it just right.  I find that same satisfaction when rock climb and eyeball a crack, find just the right sized nut to fit the nut, then feel that satisfying solidness as the nut slots perfectly jammed against both sides of the crack.

Funny how we get those little anal retentive streaks.  Like when Anya sees shoes lying around and feels compelled to have the owner clean them up.  How funny that Mother Nature should create a way of passing those behaviors in the gene code.