This is one of those issues (like hit points and movement) where the duration expression can be written in multiple ways thereby giving individual groups the option to choose what is best for their group. Perhaps something like the following:
- Encounter (1 round/level)
- Adventure (10 minutes/level)
- Day (1 hour/level)
- Etc.
Some people like abstraction in game-time, others like specifics; why not give them both?
We must have
very different play-styles. In my 30 years of gaming, I can't remember a single adventure that lasted less than a day. There probably was one, sometime, but it sure wasn't normal. Many forays into a single dungeon require camping in the dungeon, and some adventures have multiple locations. Non-dungeon adventures involve days of exploration, negotiation, spying, etc.
Storyteller had the concept of a Chapter, which (IIRC) was equivalent to a gaming session (or a couple hours, real time, for marathon sessions). That was a kinda dicey thing, but could work for the middle ground.
I think whether tracking exact duration matters is based on play style. If you have a more war-game (simulationist?) style that encourages precision in combat and good timing, then duration matters. Those same games benefit from tracking exact encumbrance (which is an eye-opening experience).
If you have a more narrative style, in which encounters serve to further the plot more than being challenging in themselves, then no one probably cares about which specific round an effect ends. The Storyteller model of Round, Scene, Chapter, Day works very well and provides all the more granularity you need.
Personally, I think the duration "saves" are one of the things that should be continued from 4e combined with narrative times for longer spells. I'd like to see a new name for them, though. It might be nice to see some modifiers to the rolls, too, to indicate when an effect is more (or less) "sticky". I wouldn't want it to go overboard, though. If every spell has a different duration DC, it's no better than tracking duration. Used sparingly, though, it could let specialist Conjurers have their summonings stick around longer, which is probably balanced with an Invoker getting a bonus to the DC of his
lightning bolt.
Really, this is probably one place where a module would be extremely effective. Arbitrarily pick a base; let's say tracking duration, because that's got the most history. Now, publish a module that follows the Narrative framework for long duration effects and one that deals with the "save" duration for short effects. There should be no balance issues with using them in the same group.
For instance, one of my players -- the one most likely to play a wizard -- hated the duration saves. But another player really liked them because she doesn't care for a lot of paperwork. Both of them could play a wizard and use a different module without one outshining the other because of it. I'm not sure whether I could split monster effects against the PCs in the same way, but I could use the duration saves without it weakening or strengthening the standard issue wizard. The same holds true for how longer duration effects were handled.