If a customer doesn't want their lawn cut while wet, that could mean literally months in some areas (see the man from Seattle on that one again). If things have become dry enough to run a mower over w/o ruts, and I'm out cutting, the lawns get done in the order they're due. If a customer wants his 'skipped', then I put him back to the bottom of the rotation ("see ya in two weeks!"), and charge him for the full month (i.e. double for the next cut, etc.).
My rates are flat monthly, so that works out much better than if I charged per individual cut. Generally, the problems I run into with rain is with customers who don't understand that rain effects the whole schedule, and not just the full day it rained and the half day next. There are too many who believe that when the rain is done, they're first, no matter what day it is, and I have to remind them they are wrong... continuously...
-TGC