i must clarify that i 'work" with combat handguns not 'duty" handguns, and there is a big difference, the Glock is a good handgun, but it is never put under any extreme stress in law enforcement agencies. even if you got into a "shoot out" and dump all your mags in a matter of minutes, I do that repeatedly in a single day at the range., using up near a thousand rounds.
now as for conditions to the above stated testing, tens of thousands of rounds, extreme heat and cold, buried, sea spray, drop tests etc etc, think of the worst things you can do to a pistol then try and fire it.