As many others have mentioned, cut anybody who does not show up for X practices. The onus should be on the kids to speak with the coach, not the other way around, especially with a large team.
I don't believe in cutting kids that come to practice, give it their best, and don't cause problems. I'm not saying you have to take every kid to every meet or anything like that.
Cutting kids based on some arbitrary time is short sighted and just seems like you are taking your little HS xc job a bit too seriously. You think you are being hardcore, but you're really a joke.
i was fat my freshman year of hs and by my senior year i had all the distance school records