I'm in good shape, but at age 62 three is my limit.
If my assignor is in a jam I can do four in a day for him if it's split 2 and 2 with a break in between; but if he needs me for four in row, I'm only working a younger age group on a small court.
And I'll be honest, that last one of the three, I'm really working hard on my concentration and making sure that I'm still hustling and working the court the right way.
Fortunately, our HS games here are only single game assignments.

One.
 

Unless I'm at camp.

Or unless I'm getting ready for camp season.

Or to fulfill my JV requirements 2 to 4 times per high school season.

Generally, though: one.