So let's take a look at this huge breakdown of a very large mount of cellar clears, separated into the game's zones.

MrFrodoBeggins certainly shows the latter as he not only completed 1270 cellars in 3 days, but also documented his loot, locations, experience gained, Treasure Goblins found, Obols acquired, Butchers encountered and more! In any case, this is a crucial post for anyone looking to complete all side quests for the zones! If you want more in-depth individual posts for each zone, with screenshots of the locations, you can also reference the original D4 forum post with links here. In the worst case scenario, you can just go through them all to check, and you might remember which you've already done along the way.

There's still the issue of players potentially not knowing which of these they've already finished. I've used this one myself to finish up a zone or two and it's extremely useful.

Luckily for us, lordhewlett has compiled all the drops and locations in this handy post (based on data by Zolmation)! Basically killing everything that moves and hoping to have whatever it is that's missing drop. And so to get all side quests completed within a zone, you'd have to scour the entirety of it. All zones have a few side quests that come from random item drops or from hard to see lootable items. This one has been a thorn in the side of completionists for quite a while now.

Diablo 2 keep the quest items