Some breeds cycle all year round - Dorsets, for instance - so the answer might depend on what sort of sheep you’re talking about.
Ex-BH used to leave his tups with the ewes year round, and got some early lambs some years but not very late ones. However, when we introduced Charollais into the mix we had to start keeping the boys separate; the ewes which were part Charollais were much more likely to cycle at odd times :/