I have pulled up the D&D 3.5 Dungeon Master's Guide to research something I was curious about, for a different post, and glancing through nearby sections really reveals to me how people who ran this game didn't do so by reading the book. It really was a passed down sort of role.
An entire section here is about how the encounters you run encourage specific play types, even if you don't intend to do so, and it gives six different "types" of encounter: Combat, Negotiation, Environmental, Problem-Solving, Judgement-Calls, and Investigation. Even this excerpt seems wildly out of place given 3.5's reputation.
Always be aware of the sorts of actions you're rewarding your players for taking. Reward, in this case, doesn't just mean experience points and treasure. More generally, it means anything that consistently leads to success. An Adventure should contain encounters that reward different types of behavior. Not everyone prefers the same kind of encounter, and even those with a favorite enjoy a change of pace.