me too. I feel I'm the only one flying the bodybuilder flag these days.
I'm primarily a bodybuilder.
Could you share some statements of truth on body part splits or training lagging body parts?
Beginners shouldn't use splits, however intermediate and advanced should use some sort of split most of the time. High frequency training can sometimes be an exception to this. Splitting workouts by which angle you hit a muscle group, but still doing full body is one way, and a good one for intermediate. Upper/lower is another very effective split for intermediate. More advanced bodybuilders should only be working everything once a week most of the time, because they need more recovery time. You can do a 3 day split with longer workouts, or you can do 4 or 5 day splits with shorter workouts. 6 or 7 really isn't optimal for any length of time though. You don't grow in the gym, that happens while resting, and you need to eat a lot and get some sleep.
For training a lagging body part you need more volume and more special techniques. For chest you might superset bench with flyes. Upper traps seem to like volume and drop sets. Calves seem to like 6 to 12 reps to absolute failure, even if some of them are half reps, as heavy as you can possibly go. Squat superset with hacks or leg extension is great for quads. For hams, just hit it with more volume. If you are forearm dominant, you might need to do slack wrist curls to force the biceps to move the whole load. A dip/skull crusher superset is great for triceps. For back, it's just plain volume. More sets is a big part of bringing up anything lagging.
I think health and functional training is important for bodybuilding. It's kind of important for everyone really. Bodybuilding mainly just requires more volume and isolation.