I feed veggies and pellets twice a day. None of my rabbits have shown any sensitivity to veggies including the gassy ones. The amount of each varies depending on each rabbit's needs. For example, Fey is about 3.5 lbs, very sensitive to protein and pellets and looses weight at the drop of a hat. In a day she gets almost 1 cup of veggies per pound (so about 3.5 cups), 2 tablespoons of Oxbow BB/T pellets, and she eats a ton of hay. Oberon is about 8 lbs- if I remember right- lazy and prone to weight gain but otherwise healthy. He gets 1/4 cup pellets and about 2 cups of veggies per day plus he eats a good-sized pile of hay. After Loki (5 lbs) started getting molar spurs I cut his pellets from 1/4 cup to 1/8 cup and increased his veggies slightly from 2 cups to about 3. Pellets don't do anything for teeth as they are just crushed but the chewing motions for veggies may help slow down the growth of molar spurs.
I feed at least 4 types of leafy greens with occasional hard veggies like carrot or broccolior small pieces of fruit. For example right now my buns are eating Swiss chard, collard greens, several types of lettuce (garden mix), carrot greens, canned pumpkin because they're molting, and occasional carrot pieces or grapes.
I think it would be better to feed veggies every day, even if it's a lesser amount, than to feed every other day. That way their diet is more consistent and the gut doesn't have to adapt to change as much.