What we see as a muscle can actually be several muscles (a muscle group), so the type of work they get will dictate the appearance, but most of the appearance is just sheer size vs. the fat that camoflauges them.
You are in a tough spot here in GQ, because I’ll give you advice, but it won’t be based on double blind studies, and others will pounce.
Work out the major muscle groups and stick to 12 reps or less to build size. What does this mean? Say you have 135 lbs on a barbell for benching. If you do 12 reps and you could have done 20 reps, you aren’t building size just because you did 12 reps.
You should have enough weight that by the 12th rep, you are toast, or nearly toast. Then on your next set, you add some more weight and fail around 8-10 reps. On the last set, you have a little more weigfht and fail say around 6-8, maybe getting a little help to get the last 1-2 reps out. You do 3, 4 or 5 sets of this benching exercise.
For big muscle groups, like the chest, you can do this type of pyramiding of sets/reps…say 3-4 sets per exercise, and doing 3-5 exercises for that group.
At the end of working the chest group, you might have done 100-125 reps total, from 3-4 different types of exercises. You can call it a day…and maybe call it your chest workout for the week. Maybe you did flat bench, incline bech with dumbells, pec deck, incline flys, etc.
Some guys will alternate light and heavy days. On a ‘light day’, you shoot for 12-15 reps before failure.