Great post and I agree. Going from 140 to 240 was simple, back then no apps, just used one and paper to add up the macros, it was mostly tuna, oats, quinoa, chicken, never ate junk just overate and got big and strong but fat. When I started AAS I thought that would change things. "Now I'm on juice, my body will utilize all these extra calories better so instead of 90% fat 10% muscle gain, maybe it can be 70/30 and I'm better off"
As the years went by I'd get to a point where it was too much, so cut, then feel small, so bulk, what many do
A few years ago I tried one last time to bulk, a slow bulk, I had dieted down to 171 (went too far no energy no libido legs hurt). Then went back to maintenance 185 I feel good still pretty lean. But did try that last slow bulk.
I forget my exact surplus but was gaining about 2-3lb a month, I felt a solid rate based on reading. Going from 185 to 210 was employable and easy I love to eat all food, clean food, love it. But still, even when going slow, the waist just shot up from 32-33 to 37-38, arms maybe an inch. Possibly just water?
But that was my last attempt at a more conservative bulk. The waist inches come fast. I'd assume it has a genetic component, I think the term is p-ratio. I also have natural igf levels just a notch from being out of range on the low end. Gh puts me in range but not even in the high end, many have higher natural igf than I'm scoring on gh
But overall that is my experience, just as you described, but the slow gaining tends to give a higher level of fat to muscle than most. Even with Alex azarian coaching me, I think we were a decently lean 220. But I still never looked like a bodybuilder. I guess the moral is genetics are king and we can all just work with what we have.
But I do feel like I see a lot of people making the mistake I did and thinking the secret is to just eat more, when in reality, like you said, the surplus must be present but it is no benefit to setting it too high thinking it will lead to faster lean tissue gain.