As there are so many factors going on, it is even tough to speak "generally" Have several bolt WBYs that use slower powders that are considerably better (accuracy and consistency) close to max pressures when using slower powders. Bought the 257 and 270 wby for their velocity, so i load them close to max. They ain't target rifles that get thousands of rounds through em.
Some medium to faster burn rate powders used in medium to smaller cases seem to be more accurate at less than max loads, especially in semi-autos. Some powders/bullets/barrels/guns have their own pressure where they operate best.