I think one can get good training and cut down on the amount of ammo.
You mentioned the Beretta so I'll address it.
Where I shoot my Beretta 92 is in action style matches, Steel Challenge ,USPSA, Run 'n Gun, etc.
These competitions take a lot of rounds but I don't believe you need to fire a lot of rounds in practice. They are timed events and where time gets you is in your reloading or moving.
So, I load mags with only two rounds, draw, shoot two rounds, reload, and fire two more. Or draw fire two rounds, move to the next target as I reload the next two rounds.
You can improve your sight picture and trigger control with dry firing. I don't have a lot of problems with shooting per se, but I'm old and slow, the reloading and movement gets me.
I don't see a lot of benefit (in practice) shooting 17 rounds, reloading and firing another 17 rounds when I loose my time in reloading. I think I get more benefit firing two rounds, reloading and firring two more, reloading and firing two more. That's six rounds vs 51 rounds if I had to do it with full mags.
I reload using cast bullets, much cheaper then using factory ammo, but still I get a lot more practice for the buck,
I would invest in a Shot Timer, thats how you measure your success in action type shooting.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071