It doesn't but trying to perfectly time your kids nap to the meeting time (she's still young and needs at least 2) usually results in a really cracky kid at some point.

Sleep is important and I try not to fuck with it when I can. So doing that when someone just cancels 10 minutes prior is frustrating and usually means I woke her up early from a nap previously to get on a good time sync.

Rescheduling to a different time that day is less bad because I can more easily keep her up another 30-40 minutes depending on the time of the day.

Basically if it's a completely different day it means she's cranky back to back days.