Hen only needs to be bred once (the result can be stored for 28 days or something like that), that doesn't mean she won't br bred again though. If they usually leave at 9:30 or 10:00 it would be to lay an egg (they don't sit , as in incubate, until all the eggs are laid). I'm not sure how things are going where you are , but here in CT they seem to be a little late do to s l o w warm-up this spring. Only in the past week have I seen single gobblers with small groups of hens, prior to that is was many strutters with a lot of hens