After training for about a year now, I am noticing I gained some muscle (not sure how much, but I'd say under 5kg/10lbs). So I would not say I am a beginner, but I'd like to add on at least 5/10lbs of muscle.
I go about 3-4 times per week to the gym, a session for every major muscle group (back, chest, legs and a session for all the rest). So far I am doing about 20 sets per major muscle groups, 8-10 for the smaller groups.
Recently I stumbled over a bunch of internet resources that suggest maybe going for less volume, and when I googled "optimal number of sets per muscle group per week" I found articles which point to 60-120 reps/week for large muscles and 30-60 reps/week for smaller ones. Considering that my sets are usually 8-12 reps (15-20 sometimes), I am doing around 20*10 = 200 reps/weeks for the major muscles and 8*10=80 reps/week for smaller ones. It looks excessive, but it's about one solid hour of workout where I rest very little (no more than a minute) betweek sets.
My question is very simple: what is the optimal number of sets/reps per week to maximize muscle gain (knowing that I am taking enough proteins) ? Is there anything on the scientific litterature to indicate or estimate that number ? What's your number from practices and what's your balance of intensity (weight) and volume (set-rep quantity) for that number ?