Mine have fresh food in the morning, and pellets in the evening.
As a lot of my rabbits are getting older they tend to eat less pellets, so to keep their condition some of them get extra fresh food of an evening too. Oscar, for example, recently had a bereavement and an illness at the same time, so dropped lots of weight (and he's 9yrs, mobility impaired, has a tumour) - he had fresh food 3 times daily to bulid him back up.
They also get to graze in the garden every day.
I believe strongly in giving them fresh food - in the wild they would graze on fresh grass, weeds etc every day. A dry diet of hay and pellets must be very boring for them imo