I dunno. I play up to 6-7 hours a day of drilling during the summer. Playing a couple 5 set matches fr me in a day is definitley doable. I used to have a bit of an issue of doing back to back days of tennis though. Even playing an hour each day for 2 days straight would bother me. Now not so much since I just worked through it.
Plus in tournaments it can be upwards of 5 matches in 3 days if you make it deep! Doubles not included!