Different stock styles usually require different lengths of pull. ie: high combs usually mean straighter stocks, less drop at the heel and thus require shorter stocks, while more drop at the comb and heal such as European designed stocks, with heads-up aiming, typically require longer lengths of pull.
Where you place the butt plate also comes into it. Some pocket the butt plate inside the shoulder 'cup' on the deltoids, where it should be, while others seem more comfortable with the butt well out on the shoulder joint or even arm with cupped butt plates, typical of lever guns or muzzleloaders- thus requiring even longer lengths of pull.

Shotguns usually have longer pulls (more drop) than rifles due to the on-the-barrels aiming- similar to European iron sighted rifle stocks.

Guess it boils down to what suits you - but - just because one type or style of gun you have has a particular length of pull, does not mean another different gun and style will 'fit' with the same length of pull. Best to try a few and decide from that.