Derren said:
When the PCs have only one adventure a week or less then it works.
But when they adventure for days without rest (except the 6 hours "heal it all rest" this doesn't work anymore.
I don't wish to be rude or anything, but Derren, this is Fantasy, not Reality. If you want delve this deep into it, then consider: after one adventure, your character would probably never adventure again. Why? Because adventuring HURTS. Alot. Pretty much as you just pointed out. And for those who do want to continue down this dangerous path, they would have to wait months or even years to recover from some of their injuries. Simply put, yeah, that's realistic, but not really fun. D&D is about having fun and being a hero. Not about watching a character sit in bed for months at a time while they slowly heal, which is realistic in our world. But, then again, D&D is not our world. It's a world of wonder and the impossible.
I understand your want for realism, and honestly, I believe D&D delivers an acceptable amount of such. But translating everything in our world into the world of D&D would just make the game slow, painful to play, boring, and not very inspiring. Indeed, why play D&D at all then? Why not just go outside and do what we do everyday with our everyday limitations?