I did try to measure this. It seemed like most people were entering perfectly reasonable dates; even things like "March" and "November"

I have a feeling it's a case of not caring how to enter the date, and not caring to try a few and find out. Much easier if you're told exactly what to do, so you have to think, because apparently checking who used the NMR machines last week is not something people want to think about. (Fair enough.)