Would be interesting if you could calculate the average healing capability of your party during one encounter, just for a high level reference. What level are they?
30th level.
In an average encounter the dwarf will use 4 surges via Second Wind/Cloak of the Walking Wounded - which are boosted by the Dwarf feat that leds him add his CON (probably +5) to healing surges, and an item that lets him add some additional bonus (CON again, mayble?) to surges when bloodied - which he will be when using Second Wind, because he wants to trigger his Cloak.
That's probably 4.5 surges worth.
Battle Cry lets the fighter and bloodied allies in 10 sq use a surge - so normally 2 or 3 when used. Running total 7.
Say the paladin uses 1 LoH per encounter, plus Second Wind (forgot to mention that, via Questing Knight paragon path, he can second wind as a free action when blooeied). Running total 9.
The ranger-cleric is obviously the big one. Healing Word is 2 surges, with bonuses of 30+on each (6d6+WIS, plus maybe a Holy Symbol bonus as well). The bonus is about half-a-surge for the fighter (60-ish surge value) but close to a surge worth for the invoker/wizard. Call that 3 surges - running total 12.
Word of Vigour is a cl burst 1, and also bring some sort of bonus with it. Normally 2 or 3 surges - running total 15.
Healing Torch is a healing effect in area burst 2 with a small bonusa as well. That would normally be the fighter and at least one other PC. So runing total 17.
I'm sure there's stuff I'm forgetting, and there are other small factors (like the invoker/wizard has a belt that grants +3 to HS value) as well as the two daily "words". But to me that looks like 16-odd surges per encounter for 18-odd surge values worth. I would say that more than half that healing is on the two defenders.
Another factor is temp hp. The paladin gets quite a few of them from some feat combo. And often the cleric/ranger is able to use Cloak of Courage at the start of an encounter to grant everyone else a surge's worth of temps.
Hopefully that gives you some sense of things.