So 6 of the 12 modules in my campaign I consider "done". These include the majority of quest content, since four of them are city centered modules and these are where most of the quest action takes place. The rest is for the overland maps (2 modules), two more city centered modules, and small modules for the endgame (four areas) and companion quests (10-12 areas).
The two remaining city centered modules need a few more trips through them trying to break stuff and catching those small things like typos or putting  instead of <> in a conversation node so it doesn't show in the right color. The endgame module should be all done but for balancing, but I want another pass through to check for bugs. The companion sidequests are relatively straightforward, but the least tested. Everywhere I've put on the overland map functions fine, but the overland maps are sparser than I'd like.
So, fellow builders, when do you consider something "done"? There's the temptation to keep adding, whether more locations and quests to a sandbox style adventure, or more depth in systems (I'm loooking at you Lance Botelle :-) ). Then you start wanting to go back to stuff you worked on early in the adventure and bring it up to your later standards. If you let it, it never ends.