I've heard that you only actually grow for 24-48 hours after training as well. This would mean it's best to hit a bodypart every third day and keep the volume relatively low, with the idea that you will be working it 2-3 times per week, always be growing and keeping the weekly total volume high. My issue with this is I'm just not interested anymore in working out every day and hitting each muscle 2-3 times per week. I'm willing to train in a way that gives me slower progress, I just don't want to regress.
For natties only...
This is the logic behind training full-body 2-3 times per week, but only do 1-2 exercises per bodypart.
The problem for most when they train full-body is they do too much in a workout. They bring their split volume to the full-body routine. Too much.
You only need 1-2 exercises per bodypart, 3-5 sets per exercise, 20-40 sets or so total per day.
There are let's say 8 bodyparts...quads, hamstrings, calves, chest, back, delts, biceps, triceps (not including abs).
Squats
Leg curls
Calf raises
Dips
Pullups
Dumbbell press
Barbell curls
Tricep pushdowns
3-5 works sets each. 24 to 40 work sets per day.
This is the way bodybuilders trained up to mid 1950's before D-bol came around (except for pre-contest more volume to lean up). The old timers had a lot of mass (reasonable) even though they trained this way.
Drug users, on the other hand, can go crazy with the volume and recover. All the 5-6 day mega volume split routines in the mags/interwebs are for drug users. The "Arnold" routines are for drug users. The 1-day per week mega blast routines are for drug users.