Standard bet sizing all around has changed a lot since the early days of poker whether in cash or mtt. I assume a big part of it is because of a better understanding of theory in poker, but I haven't been able to find theory material explaining those changes in standard sizing.

The only thing that seems to come up is the classic "polarized range vs bluffcatcher on the river" toy game, but I would like to know the reasoning behind sizings in more common situations like for example just raising/3betting/4betting preflop or cbetting the flop.

Can someone point me towards the right direction or is this some secret that high stakes players figured out and are keeping for themselves :p ?