Dreamchaser, the issue is not time between encounters. It is encounters per day.
PCs don't use Second Wind to heal outside of combat, and never need longer than 5 mintues to fully heal if they're doing it under their own power. According to the PHB on p. 293 (Lower left beige box, first paragraph, third sentence), "After a short rest, you can spend as many healing surges as you like outside combat." That's it. Short rest, spend as many surges as you like, get back to full. It happens instantly at the 5 minute mark.
What's making people take longer "short" rests is trying to maximize the effectiveness of their healing surges with Healing Word. The issue comes into sharpest focus, I think, with rogues.
A rogue I ran in a test game started out with 7 healing surges and 24 hit points (so surges are worth 6). He was heavily encouraged, by the flanking rules, to get into melee, but poorly equipped, by the armor rules, to handle the punishment. So he lost most of his hit points most fights. Without a cleric in the party, he spent 2 - 3 healing surges per fight (either during or after), and so was really only good for 2 - 3 fights per day.
Now, suppose I'd had a cleric around. The cleric in my current group is run by a mathematician who has bent all of his analytical skills toward maximising the output of his healing. He often grants +12 or +15 to a healing surge, and is currently dredging Adventurer's Vault for items that give a stacking bonus to healing (and he's found a lot). Well . . . that would effectively double or triple that old rogue's healing surge value. Before, he was good for 2 - 3 encounters. After, he'd easily be good for 6. Maybe more, given how much free healing and temp hit points that particular cleric hands out. In practice, he'd never run out of surges. He'd reach a lull and stop to get dailies back much sooner.
Which, incidentally, is exactly what happens in my current party (the one with the awesome cleric). We never rest due to healing surges getting low. Never. We'll do 3 - 5 encounters per day, and even the most fragile characters won't use half their surges. We usually rest due to wanting dailies back (and free action points!), or sometimes because we've done all the encounters in the dungeon!
In my mind, this is an indication that using Healing Word during a rest--while legal--is too powerful. For resource management to be interesting, you should usually run out of those resources at the same time. But I'm just not willing to go 8 encounters (till my surges run out) on one or two dailies! And besides, what other class gets a "double the whole party's effectiveness all the time" type power? That's just craziness!
Don't get me wrong, I love that healing rocks now. But the out-of-combat Healing Words bothers me from a game design perspective. Of course, I love them as a player . . .

And kudos to our munchkin cleric, for having found--right off the bat!--probably the most effective party buff in the game.