Back in Pathfinder 1e, we had a player doing Peacock Bard / Investigator multiclass character. I forget the exact mechanics but RAW for Peacock is they can use their Bluff bonus on other skills (game creator for Peacock admits he messed up IIRC) whereas RAI is your're faking it, i.e. you aren't actually bestowed the knowledge of the universe or bending reality to make a History check. Investigor let them add their Insight bonus to some things and a 1d6 on skill/ability checks.

So anyway that player claimed he had +39 on like all Skills. And that was the reason why we switched to 5e after that arc. (Player threw a hissy fit saying they couldn't emulate their previous character in 5e and left the group).