With my group it really all depends upon what and how much there is for the tortoises to eat in their habitats.
With the Aldabrans I give them a once a week feeding of Mazuri, but other than that I don't feed them at all.
The leopards, steppe tortoises, Dudley the sulcata and the desert tortoises only graze. I occasionally cut branches off the mulberry tree and toss in their habitats.
Along with the grazing, I feed the Manouria about once a week a large meal of fruits and veggies.
My tortoises' yards are pretty big and there is plenty of grazing material for them.