This seems a little silly and possibly pedantic, but as I was writing an answer to An initial stealthy/surprise attack with subsequent adventurers entering combat afterwards?, I looked to find rules for resolving non-combat situations where action order is important (or useful). Particularly, I was looking for guidance on when to let the party set their own order as opposed to requiring initiative rolls. To my surprise, I couldn't actually find anything about using initiative order (or for that matter any sort of order) for exploration or social interaction — the other "Pillars of Adventure", as PH page 8 puts it.
Examples might be:
- an argument or debate, possibly where the party is not in agreement
- exploring a cavern where the DM wants to increase the sense of suspense
- as in the other question, sneaking up on someone before combat is started (possibly even with the possibility of avoiding combat)
- rescuing people from a burning building
- establishing reactions to a surprise event (the town hall across the square explodes! what do you do?)
- interaction with a timed puzzle which is not a danger per se
(In some of these cases, I can imagine guidance suggesting not using initiative order, and why or why not.)
The only bit I can find is under "Time" at the beginning of Chapter 8, which says
In combat and other fast-paced situations, the game relies on rounds, a 6-second span of time described in chapter 9.
Chapter 9, of course, is the Combat chapter. Is there more in-depth guidance for ordered rounds as a measure of time in "other fast-paced situations" somewhere in the DMG or elsewhere? Or are we just expected to use common sense for this? Not that there's any problem with that — it's certainly been the practice at every table I've played at — but I'd like to be aware of anything that does exist, particularly when offering rules-based advice to other people.
To put it another way: sure, many of us with experience playing D&D and similar games have many ideas about initiative as non-combat instrument. But if D&D manuals dropped through a wormhole to a parallel universe with no existing D&D culture, how would people know that this is what they're supposed to do?