Getting stronger for reps is a bodybuilders way of monitoring muscle gains. Maintaining strength is a way to monitor whether you're maintaining muscle on a diet. As simple as this sounds, it works! More load (for a certain total time under tension/TUT) = bigger muscles.
Quality, and load going up over time, trumps quantity. Many newbies have plenty volume, but lack the required intensity/focus/load for growth. Don't be worrying about pyramiding schemes etc when you aren't even pushing it to the max and adding weight to the bar over time.
Same goes for the amount of exercises/sets per body part. If you haven't even mastered your mind-muscle connection, or consistently added weight to bar on the basic bread and butter exercises, how do you expect that millionth (redundant) exercise to do any better at stimulating growth? Especially after you're probably drained by that point and lacking the required drive to adequately overload the muscle? People add exercises for a specific reason, not just for the sake of it.
Don't underestimate the amount of calories needed for good muscle growth. No routine will work without pushing your bodyweight upwards. It's no use worrying about anything else, complicated crap, when you simply aren't consistent with your diet and eating enough over a long enough period to make the scale go up.
Don't think you can stay ripped all the time while gaining. Ripped = body fighting to add fat. Bulking = the body easily adds muscle, but isn't fighting to get fat back up.
If you were to bulk up from being really lean, it wouldn't take long at all before the body increases fat levels to a "comfortable" level (sometimes called the "set point"). Thus, if you wanted to remain really lean, the bulking phase would be cut short and wouldn't last long (no adequate long term growth and strength gains). Bulk/gain at a comfortable bodyfat range.
It you don't hold a strength level/muscle level for a decent enough time (i.e. eat enough for it), your body decides it's not necessary and drops it. So don't do extremes - quick and frequent cycles between heavy bulking and then sudden extreme dieting. Just gain at a decent pace (strength/weight gains comes in peaks/lows) and maintain it for some time, trim a little when needed, then repeat. Trimming a little is fine (when it doesn't affect strength) but don't diet to very low bodyfat levels until you are big enough to be happy with it. Remember, being ripped isn't usually a case of losing just 5-10lbs lol
It doesn't matter what your genetics are like, the principles still apply; you will always gain some fat while gaining, whether you're genetically lean or not - this is why you have a bodyfat range while gaining, not just keeping at the same amount of fat.
Some need more food and others need less. For those who need a lot less food, quality and timing (carbs mostly around active times and the morning) becomes more important. For those who need a lot more, they can get away with more "dirty" foods without it spilling over much into an unacceptable rate of fat gain.
Bodybuilding is all about making every body part grow, yet if you hardly over-load the target muscle by the end of the workout, how do you expect it to grow really well? Do you focus on the target muscle and feel/visualise it working (not just moving load from point A to B)? Do you control the load (no bouncing/momentum) with the target muscle (especially on the negative portion)? Do you actually directly train it AT ALL (e.g. arms/delts etc)? Don't even think about specializing on body parts until you get those basic bodybuilding principles right first.
This is the reason why bodybuilders split things up - it's not just due to some misguidance, or coincidence or something that only people on steroids do! Body parts need enough attention to grow. Making a body part grow a lot takes adequate stimulation/muscular over-load/focus...and then adequate recovery. Some people prefer more body part volume/frequency, and others prefer less. This is all part of learning your own body.
He who focuses on his exercises (uses them as tools and picks a decent enough one that his body likes), and adds weight to them over time etc is going to make much more progress (muscle) than the one who treats his workouts like some sort of game/ride/fun fair attraction where he gets bored within 2-3 weeks of doing it and switches to a new "amazing" exercise he's read about. Or the one who's that obsessed over a certain exercise that's just not co-operating (either due to the way it's done or body mechanics)...and thus not progressing on it. Do your exercise for long enough, take it seriously and get strong with it.
No exercise trumps every other one...no, not even the beloved deadlifts that you do to just to get an ego boost Progression is what matters. There are really good, solid exercises (bread and butter movements) out there, but don't be too narrow-minded, or think that that's all you'll ever need for a certain body part, especially as you get more advanced.
After spending years on the squats, and you have no leg development to show for it other than a huge ass and injured lower back...why would you claim that the leg press is an inferior exercise to squats? Even if you did it along with squats? Progress is what matters. If you feel it in the target muscle, if the target muscle grows really well from it, if you can add weight/reps consistently....why would it be an invalid exercise?