Obviously you have no experience in certified law enforcement training in California. Special assignments with special skills such as SWAT or traffic collision investigation require certified training approved by the California Commission on Peace Officer Standards and Training. The training conducted by most departments on their own is related to practicing and honing those skills learned during the state certified training course which was presented by the FBI at that time. Those training courses (such as sniper training) require a full course outline down to the 3rd level and including sniper tactics, shooting positions, scope use, mental preparation, etc., including care of the rifle. This component is very important since the rifle is responsible for 95% of the success of the shot. Abrasives will remove powder and fouling but won't reach into the rifling grooves to remove copper that's been squeezed into them. Copper fouling always requires chemical removal, thus the plethora of special bore cleaners containing ammonia or similar chemicals intended to dissolve and remove the copper. Police training in California is very heavily regulated and controlled due to the significant liability faced by law enforcement agencies in use of (deadly) force situations. Additionally, since many agencies can't afford their own SWAT teams and snipers, they use regional teams often provided by county sheriff's departments or multi-agency agreements, thus, you don't have "thousands" of snipers, more likely a few hundred. Sniper certification courses are usually offered only once or twice a year since there are so few of them and the turnover is very minimal. I hope this gives you some insight into a special world that very few people get to experience.