Depends if you are talking feeding in an open lot, confinement building, limit feeding, full feed.  If in open lot or limit feeding best to have plenty of bunk space to make sure everyone gets their tummy full of fresh feed.  If feeding in confinement cost of the building becomes a big factor. At $400- $500 per running foot for a 40-50 foot deep building, feedbunk space does become a factor.  Payback over a 10 year period is $40+interest to $50+interest per animal/year if using 1 foot of bunk space and $80+interest to $100+interest/animal/year if using 2 foot of bunk space.  Cattle in confinement are a funny animal, they will get up and come to the bunk anytime you drive by with a tractor, pickup, or what ever, when ever.  We feed in the evening, works best for our schedule, and strive to have the bunk empty just as we drive up with the wagon.  If the bunk is licked clean we will increase the diet by a pound and feed at that rate until they once again have it licked clean.  Very seldom during the day is there not at least a few cattle at the bunk and very seldom is the bunk  full when feeding for more than a couple minutes.  I maybe wrong, but I think it is better to let the animal eat when he wants not when I want him to.