One of the things I've noticed in terms of set-up is that what seems absolutely right might be good, but might not be the best at any given time.
I have a son slightly taller and still growing. Sometimes we leave his (or my) bike on a turbo and do consecutive sessions. A 'real cyclist' might say this is wrong, but I started to ride many years ago and there were no 'real cyclists' back then.
My son rides an old bike of mine (adapted to fit) and I occasionally notice things that I might alter on my own machine after a ride on his. Little things, but they all add up.
Occasionally, it helps to mark the position of everything and then put everything way out of adjustment and start all over again. marking is tricky in terms of the tilt of the bars and one or two other things, but many adjustments are 'markable', particularly if the components are old and have pinch marks in key places.
Once everything has been deliberately wrongly adjusted, the whole set-up can be done again.
Seat height, seat fore & aft, seat angle, bar height, stem length, bar rotation....
It is not always as it was.
Add to this the reality that some high-mileage riders like to have a little shift in set-up every now and again and the whole fit thing becomes more of a variable than a right-wrong equation.
Some people clearly get a lot out of having their set-up examined and set by a professional. I suspect my resistance might be fiscal prudence as much as it is pride.... But I still like the old 'suck it and see'.