When I started playing with it all day I would shoot maybe 50 rounds all day. Against semi autos or stock guns. Now that I have improved in skill with it, I shoot between 100-200 in a day. I change 12 grams every 20 shots, and sometimes between games if I wasn't sure how much has been shot.
Right now I am preparing to make my PGP constant air and regulated for days when I play against semis, and use a phantom quick changer for 12 gram days.
It's signifigantly cheaper than pump or semi, if that's what you want to know