It all depends on your mentality and physical condition. If you can stay mentally and physically focused for 2K rounds then each round will benefit you. If you're only focused for the first 2 minutes / 10 rounds at the range and then you loose it, then your really just wasting your time and money beyond those first 10 rounds.
I've spent whole days shooting in classes and otherwise and have gone through well over 1k rounds. I definitely benefited the entire time.
On a regular basis I'll typically shoot about 300 rounds a session. I could probably handle more but I couldn't afford to do more than that with the frequency in which I shoot.
If your anything like me, somedays your mentally into it and other days you may not be. The days your not should be short so as to keep from picking up bad habbits.