It depends on your tolerance and pocket book.
After about 100 to 150 rounds I get tired and well, I start wasting ammo.
It all depends on what I am practicing. If all my shooting is from a concealed holster I'll get tired quicker. Or if I bring swingers/poppers/movers or such to practice on.
Find your limit where when you start getting tired then pack it up. Safe the ammo for the next practice session.
“We can evade reality, but we cannot evade the consequences of evading reality” Ayn Rand