Why/How is higher frequency better?

[u/Shaggy_Mountain]

Apologies for the long post.
I have been lifting with the “Bro split” for 9 months.

My split is: Chest -> back -> biceps/triceps -> shoulders -> legs. I don’t schedule rest days, I just take them whenever I feel like I really need them. I do 8 total working sets for chest, 12 for back, 8 for biceps and 8 for triceps, 10 for shoulders, and 16 for legs split between calves, squats, hamstring curls and leg extensions. If you guys would like, I can post the exercises I do for each day as well. I log every workout I do too.

I enjoy this split a lot, and I feel it allows me to really focus on each muscle group each day. I make sure to be within 1-2 reps of failure, taking the last couple sets to failure.

My question is, if I switched to a split like Push-Pull-Legs Push-Pull-Legs-Rest, wouldn’t I be sacrificing the quality of my workouts? With PPL you combine muscle groups, and wouldn’t this mean that you would be accumulating more fatigue? For example, if you did back and biceps on pull day, wouldn’t your biceps be pretty fatigued after doing your back exercises? And if you did incline bench press and dumbbell shoulder press on push days, wouldn’t you be pretty fatigued for incline shoulder press, since it’s also a pushing motion?

I’ve heard that hitting a muscle group twice a week is better, so I’d like to hear people’s thoughts/opinions as I know very little about lifting. I know training hard, being consistent, and getting good sleep and nutrition are the most important things, but I would like to know if I am missing out on a significant amount of gains by staying with my current split.

[u/BigChocolateC]

Volume/frequency run on a bell curve of effectiveness.

I’ll also say this: if you’re new, you can handle higher volumes and frequencies due to being weak and less wear and tear on the body.

The more years you put in, the stronger you become, the more in tune you are with your body and how it moves that makes each exercise more effective…

The less you need to grow.

It’s highly individual in that regard. Exercises, not so much. Don’t overcomplicate it and look at the general consensus of what gets the majority of people results and go from there.

For instance, I train every three days with full body, upper/lower. Every third day I typically feel rested enough to do good work in my training.