We often see criticism of the need to use decimal for things like temperatures. That is, the degree Fahrenheit has some special property meaning we only need whole numbers. But Celsius is criticised because we often need 0.5! That might have some truth in terms of room temperatures. But none at all when it comes to cooking!
Probably the greatest number of non-metric spanners/bolt heads are actually not whole numbers. Worse, you have to go up and down the scale from eights, through quarters to halves. (Worse still if you are going down to sixteenths, thirty-seconds, etc.)
⅛, ¼, ⅜, ½, ⅝, ¾, ⅞
Then, if we go down to even smaller measurements, we miraculously jump to thousandths! How many thousandths in a sixty-fourth? Horrible.