Classical discrepancy

Is there an assumption about improvement trajectories proportion in the pool(s)? that we would all improve the same amount per game, on average? I think I sub read that. We may not have all the same chess birth age, and degree of presence or ability to learn from experience for all sorts of non-chess reasons or habits of digesting or internalizing or learning from a given number of games. What if too many games next to each other, for example. like watching 2 dense movies next to each other. I would have at least wasted my digestion of one of the 2 if not both.

In all honesty, if you are telling me that on a blitz binge where a person might play 10-50 games straight he is "serious" about each and every one of those games as much as he would had he played a single 45+45 then I might retracted. I just don't buy it. That is, that it's even possible.
I have something to add but I'll do it later, in a private message.
Anyway, to each his own.
Cheers.