I've found this thread interesting, because I've never really noticed the 15-minute workday being an issue. Strictly discussing D&D for now, I honestly believe that the problem isn't the magic system, the hp system or anything else systemic, but - as suggested by others here - the design of a typical encounter and the approach of DM's to how NPC's act and react.
Anecdote: we've just run a 2nd-level party through the Rose Quarry suite of encounters in Shadows of the Last War... and we did the lot, in a session, without a rest.
So... that's a total of 13 Glass Zombies, 11 soldiers (2nd-level warriors), 4 skeletons, 1 2nd-level necromancer, 1 2nd-level fighter and 1 5th-level cleric. Quite a handful for 5 2nd-level characters (particularly when one of them only meaningfully acted twice in the 30-or-so total rounds of combat, but that's another story).
Because the players
and the DM assumed intelligence of the part of the NPC's, the player characters never believed that they'd be able to take out a handful of bad guys then rest up. Everybody worked on the basic assumption that if any of Team Evil went missing, the others would go on high alert; patrolling the area better, setting up traps, potentially getting reinforcements from somewhere and generally digging in. So, despite the massive odds, the PC's devised a strategy that treated the entire village as a single encounter, divided into a series of set-piece battles... and working on the basis that whilst we were in one fight, the people we were up against
could and
would make intelligent choices and call for aid from their associates, which they did.
And at the end of all that, once we'd beaten the rather large roster of enemies, we still weren't out of options. We could easily have handled another fight or three. The adventure as written, from what I could glean, a) assumed that a 2nd-level party couldn't and/or wouldn't take on the main force in the camp, and b) that they'd go from one "encounter area" to another, killing things and then retreating to rest up inbetween. However, given the total size of the area involved and the noise associated with combat, everybody around the table agreed that the notion of dispatching one group without alerting another was simply preposterous.
/Anecdote
The point I'm making is that nobody treated the NPC's as "mobs" who remained inactive until the PC's entered their little area, which meant that the player characters weren't making assumptions about being able to blow all their resources in a single fight.
If you're going to try to design encounters to encourage a longer working day, it's actually easier to do at low levels where you don't encounter you-must-be-this-tall monsters. If the PC's continually run up against creatures that require a particular buff in order to fight effectively, once the party's capacity for that buff is exhausted you've pretty much given them no choice
but to rest up.
Another issue seems to be what level people pitch their encounters at. Now, I admit, I've only been thinking about the meta-aspects of encounter design since coming here and reading the sort of stuff that Frank and K post, but - almost by chance - I have always designed adventures and encounters around the notion that
most of what the party encounter is less tough than they are. And so, I suspect, a significant contributing factor in why I've never noticed a problem with the 15-minute working day in all the years I've been running D&D is that the majority of the threats my PC's encounter are below their CR.
They spend most of their time not busting out the big moves... and then every so often they'll hit something with a CR/EL two or more levels greater than the party level and all their best stuff comes out.
Here's an article on that very subject that I found quite interesting. For those who can't be bothered to go and read it all, I've quoted the salient argument here:
The Alexandrian wrote:
MISREADING 3rd EDITION
So what happened in 3rd Edition?
As far as I can tell, everybody misread the rulebook. Here's what the 3rd Edition Dungeon Master's Guide had to say about "Encounters and Challenge Ratings" (pg. 100):
A monster's Challenge Rating (CR) tells you the level of the party for which the monster is a good challenge. A monster of CR 5 is an appropriate challenge for four 5th-level characters. If the characters are higher level than the monster, they get fewer XP because the monster should be easier to defeat. Likewise, if the party level [....] is lower than the monster's Challenge Rating, the PCs get a greater reward.
And a little later it answered the question "What's Challenging?" (pg. 101):
Since every game session probably includes many encounters, you don't want to make every encounter one that taxes the PCs to their limits. They would have to stop the adventure and rest for an extensive period after every fight, and that slows down the game. An encounter with an Encounter Level (EL) equal to the PCs' level is one that should expend about 20% of their resources -- hit points, spells, magic item uses, etc. This means, on average, that after about four encounters of the party's level the PCs need to rest, heal, and regain their spells. A fifth encounter would probably wipe them out.
And, at that point,
everybody apparently stopped reading. Because this was what seeped into the collective wisdom of the gaming community:
Every encounter should have an EL equal to the party's level and the party should have four encounters per day.
I literally can't understand how this happened, because the very next paragraph read:
The PCs should be able to take on many more encounters lower than their level but fewer encounters with Encounter Levels higher than their party level. As a general rule, if the EL is two lower than the party's level, the PCs should be able to take on twice as many encounters before having to stop and rest. Two levels below that, and the number of encounters they can cope with doubles again, and so on.
And if that wasn't clear enough in saying that the PCs should be facing a wide variety of ELs, the very next page had a chart on it that said 30% of the encounters in an adventure should have an EL lower than the PCs' level; 50% should have an EL equal to the PCs' level; 15% should have an EL 1 to 4 higher than the PCs' level; and 5% should have an EL 5+ higher than the PCs' level.
But all of that was ignored and the completely erroneous "common wisdom" of "four encounters per day with an EL equal to the party's level" became the meme of the land.
People are very keen - and rightly so - on the idea that D&D adventures should be at least a little consonant in how they play out with the high-fantasy sources that the game draws from. Thing is, whilst your major heroes in fantasy novels may potentially fight many a long battle before stopping to rest,
how many of those battles are with opponents of equal calibre?
Now I'm not claiming a widespread review of the literature by any means, and a lot of people here can doubtless produce counter-examples straight out of their heads, but in the handful of books I've pulled off the shelves and flicked through (Conan, some of Eddings' hogwash, Fritz Leiber, Feist, Tepper, Brooks) it looks to me very much as though the main protagonists are mostly facing enemies who are significantly weaker than themselves. They are, by and large, facing enemies that don't
require them to bust out their big moves, and so they don't. They tend to spend some time beating on mooks before having one combat where they're facing a real threat and need to pull out all the stops before retiring to lick their wounds. One significant devation is, tellingly, Jack Vance's
Dying Earth series, in which characters typically
can only manage one combat encounter before having to rest, but that's to be expected.
I tend to set adventures that take the fighting-weaker-opponents principle even further than is recommended in the DMG. I reckon probably 60% of encounters are with enemies of around CR-2 to CR-3, and I would generally expect my gaming group to plough through maybe 8 encounters (including one really tough one) before resting. Is this down to encounter design, player attitudes, some combination of the two or none of the above? I really don't know...