I don't think there is one schedule that works all of the time.
If the weather is warm and the tortoise is active, feed him regularly. Give him good foods such as weeds and greens, with calcium added. If the weather is cool and he is less active, give him the same foods but in smaller amounts and fewer meals.
I know that sounds simplistic, but that's the way it goes. During the summer when my tortoises are outside I would feed them almost every day. Over the last few weeks I fed them maybe once a week because they were indoors and shutting down for winter. If I had tried feeding them 3 times a week (for example) during the entire year, then there would have been a lot of wasted food in the fall.
As for how much per meal: If there are leftovers at the end of the day, then you are feeding too much. It seems that overfeeding is my biggest problem, so I rarely worry about underfeeding. When my torts are outdoors they will eat lots of grass in their pen, so they always have something to eat.
If the tort gets fat around the legs and neck, so that it is hard for him to pull into his shell, then you are over doing it.
Also, if the tort seems sluggish even under good conditions, then you might be overfeeding. This seems to happen when my torts are indoors and eating pelleted foods.