You do not need to Squat 3 days a week, rather throw in a Day of Extension/leg curls. Some will do flat press one workout day and Incline the next. Each workout on a full body workout does not need to be the same. I like doing 3 sets per exercise on full body. I also found a 3 day split very productive training Chest/back off Shoulders/arms off legs, weekend off with more volume. plenty of rest time.
as a natty, 3x a week of full body (im assuming that means one or two real exercises like bench and flies per bp) i feel is too much. i wouldnt be able to recover. i would need to eat ALOT and since im an endo with lousy bb genetics, I would end up looking like shit.
For me the split has been
mon- bench, overhead press
weds-weighted pull ups, leg press, and some form of a deadlift if my back is feeling ok
fri-bicep curl, overhead single dumbbell extension for triceps
for the poster who asked about reverse pyramid sets, its a way of gaining strength.
theoretical bench would look like this:
225 x 5 (5 hard reps but possibly with a spotter u could have gotten 6)
10% less on second set (6-7 reps)
10% less on third set (8 reps)
thats it for chest. as i get stronger i will add in a couple sets of fliers or something but for now this is providing results. the next bench day you would increase weight or reps