CapnZapp
Legend
First advice: whatever you do, keep it simple.One player thinks the fights should be shorter, since I've been running fights that were Level + 2 recently, 4 times a day. (Though I think the players could be much quicker with their decision making, but they're all new RPers, and we've been having big gaps between sessions recently.) I'm not entirely sure if I've struck the right balance there, but Level + 0 is way too easy.
Then; after several dozen sessions I have concluded the game is intended to be run in a certain way.
If you can manage four or five encounters each session (averaging less than an hour per encounter) this is the intended way to run the game.
Then the game truly becomes a resource management game: each encounter may not be very challenging, but holding on to your dailies and surges while still defeating the opposition becomes the game's real challenge.
This works best in the classic dungeon setting (which IMHO is the only setting the game truly supports) - where encounters are close to each other, and where taking extended rests can't be taken for granted.
So you're "supposed" to manage four or five encounters (or three, or seven, but you get my point) before each extended rest. IMHO, this is where the game's balance point is - where dailies and surges have just the right impact each.
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Me and my group fails at this miserably, being far too fiddly and slow; so don't worry if you don't recognize yourself in the above.
We only manage two encounters a night (or possibly three). Thus the game's default assumptions doesn't work for us.
If we only do two encounters a session, those two encounters better be harder than level+0, or we'd go through entire evenings without real challenges.
So you see, there is a reason for that level+0 baseline. It isn't strangely easy; it's easy because you're supposed to fit in five more of those during the same day (both in game days as well as real game sessions).
If you can't keep up that pace; you should feel free to make changes, just as I had to do. That doesn't mean you're playing the game wrong, or that the DMG guidelines are wrong.
It's just that the DMG utterly fails to explain the rather large set of assumptions the game is based on.