One if the things about FB workouts is that it depends on your goals. Most of the FB workouts that I have seen talk about heart beat and strength----killing 2 birds w one stone. I believe you can do this to a certain degree but not a really high level.
Even Mentzer talked about how weight lifting should not be aerobic at all.
I would say this is common misconception. Yes, alot content on full body routines is more conditioning or circuit based. But this doesnt mean it has to be that way. Full body can be hypertrophy, strength, or whatever goal oriented. All depends on the weight used and rep ranges, rest pauses etc. Ive come acustomed to doing alot supersets to get more work in in less time.
Like first couple and heaviest exercises I do regular style. But after that I couple exercises to get more work in in less time. Biceps, 1 min break, triceps, 1 min break, biceps, 1 min triceps . Back and forth like that.
Reverse peck deck with wrist curls. Lateral raises with back extensions. Squats with calf raises etc. I usually work out for like around 2h and i get alot work in like this. And sweat like motherfucker. But most exercises i use weights that i can do 5-8 reps and always go very close to failure.
Good exercise selection / form, intensive training, heavy weight, progressive overload and training consistency . Gaining strength and muscle
This is not the most couch potato friendly routine perhaps because high intensity and volume but I really enjoy it. That i can work out basically 2x week and progresss in strength and muscle. And the full body pump, the exercises, etc, I love it. I dont go to the gym to scroll my phone