I dunno, we only have one ice surface, and we were able to build in an hour of practice at noon. It all depends on how big your competition is. We ran a test session on Friday morning, had afternoon practice ice and started competition events around 5 p.m. or so. There was early practice ice on Saturday, and more at the noon hour, but none Saturday evening because the competition ran fairly late. Some practice ice Sunday morning, events until about noon.
I live in a part of the country where rinks are quite far apart. We all run at least some practice ice with our competitions because there's no place else to go.