I am using a workout routine to gain more muscles in the upper body. For many months (5 so far) I've been following a plan which caused a 2cm (almost 1 inch) girth increase in my biceps and forearms but I think I could get more. I am following a healthy diet (lots of protein, vegetables, healthy fats e.t.c.). The plan I'm following says to work out twice a week (Mondays, Thursdays) for about 45 minutes (first 5 minutes is a warm-up). It's a full body workout. 4 sets with 12 reps per each muscle group. And I gained these 2cm but in the mirror I see nothing. My current age is 36.
On the other hand my lower body, especially my legs are extremely well built, full of muscles and almost no fat. And I gained these muscles when I was young (around 15). I didn't follow any diet and no workout plan at all. I was riding a bicycle, about 30-50km a day just for fun, sometimes faster, sometimes at slower pace. I was eating whatever I found in the fridge (and not directly after the ride as I never feel hungry directly after a physical activity). And sometimes I was eating only 2-3 times a day, big meals (not 6-7 small meals like it's recommended nowadays). And I didn't have 2-3 days for muscle regeneration as my workout plan recommends. What's more - my plan says (and many articles on the web) that cardio is bad for muscle gain but... this is actually what I was doing on my bicycle, right? My legs are full of big muscles until today although I don't train them too much now. I built them doing cardio for 1-2 hours everyday on my bike. Maybe the key was in my diet? (I was eating a lot of potatoes and bread during that time).
What's more: my friend is a physical worker and he doesn't go to the gym but he just uses his muscles at work for 8h a day. 5 days a week. No breaks for regeneration, no special diet and his upper body is really well built.
And I can show many more counterexamples like these that contradict the modern workout plans that recommend to avoid cardio, sleep a lot, work out every 2-3 days for 1h max. So is there something wrong about the current recommendations for body building?