I did a few adventures. Then I realized how much I rewrite adventures, and got rid of most of them, save for a few gems and curiosities (Greyhawk Ruins, Caverns of Thracia, etc.).
Now it's all setting material, all the way down. Since I primarily use the Realms (and a dash of Greyhawk), that's a LOT of 1e and 2e books. I make use of the setting material to pull dungeons, sites, and NPCs and convert them as needed. Notably, I keep my games pretty loose rules-wise, and I've found that if you simply take any NPCs' Ability Scores and subtract 10 from them, that's as good an indication as anything as to their modifier on a d20 ability check, attack, or save, so that saves me a ton of time on conversion work. I only do a full conversion when it's a critter that doesn't have Ability Scores and/or I know it's going to feature prominently in a set-piece encounter.
I have the 4 volume Encyclopedia Magica series, too, and use that for all magic item table rolling. That means I do have to convert magic items somewhat frequently, but finding a direct correlation is easy enough, or just relying on simple things like "+1 to +3 to such and such" or "advantage/disadvantage when such and such" goes a long way. And I don't mind magic items "breaking" some standard rules, like using modifiers in place of adv/disadv, so that too keeps it both simple and direct, as well as making such items feel different from character's Class Abilities and the like.
I also use B/X (via Old-School Essentials) for stocking dungeons. I take a lot of liberties so I don't stick to the rules entirely as-is, but I use that as a gauge for treasures and which rooms have what monsters or features. Then I rely on
the Event Die, wandering monster tables, and 10 minute segments (formerly known as "turns") and 4 hour shifts (in the wilderness) for determining how often to roll the Event Die.
