You don't have to know the exact formula in order change the way you do things. For instance, if I knew that pummel was vastly more dependent on strength compared to dex, and I wanted to make sure my pummels always stay nice, then I might wear more STR gear than DEX gear. Vice versa if DEX were the main stat. And I didn't have to know the formula to make that decision- all I needed was something like, "Strength and dex both matter, but strength more than dex."