I played 27 holes yesterday. I play golf with a group and occasionally we will go out of town to play. We try to get the earliest tee time available where we are going, even if this means we have to leave home at 2 or 3 in the morning. We have been known to get 54+ holes in same day, spend the night, play 36 next day and drive back home.
A few years back, I went to Myrtle Beach. Flew in on Friday around noon, was there all the next week and flew back on Saturday night. Was there 8 nights. I played 15 rounds. So, I almost averaged 36 holes every day.
Since all of this is happening during the summer and dealing with high heat and humidity, best advice I can give anyone is stay hydrated. It is a must to drink lots of fluids. I mostly drink water and Gatorade. For ever bottle of Gatorade I drink, I will drink 2 bottles of water. I also like to have some sort of salty snack at least a couple of times during the day, something like Fritos work good for me. Since I am Type 2 Diabetic, I take pills for my blook sugar. So, it is a must that I eat something before I start playing or else I will get low blood sugar shakes. I just don't like to eat anything heavy.