It appears that a '6' heals a 24 YO at about 7 days per week of injury.
I had a '1' doctor when I got my first significant injury a 4-week injury to a 20 YO. I ran over to the Staff and there was a '9' with an outrageous salary, so I waited a week, and the 20 YO didn't change at all. I then got my current '6' and it appears that the 20 YO is taking about 5 days per week.