As I was retiring the job was testing the next generation Glock (with the angled extractor that had the chambered round indicator nub). During my last summer qualification all shooters on the line finished up and then were given the prototypes and fifty rounds to fire. Malfunctions and the prototype serial number were noted on each shooter's score sheet. RO said the goals was 10,000 rounds per EACH prototype and I saw 25 prototypes on the line that day. I was told there were many more prototypes in testing than that. That's a hell of a lot of ammo and testing.
Thus, both rookies and seasoned officers were shooting the gun for testing purposes Rodman's neck is an outdoor facility so you are shooting in all climates all year long.
In my opinion if a pistol survives all that the NYPD throws at it it's good to go.
As to a 15 round model 17 it's ludicrous to me, but the JOB has always required that all service weapons have the same magazine capacity. That's from the puzzle palace.