You're pulling everyone's leg right? No offense, but you can't be serious. Your comments about sparring are analogous to telling a baseball player, for example, to work on/hone his batting skills by just playing scrimmage games instead of spending quality time isolating, analyzing, and honing his batting skills through specific, isolated batting practice (which, by the way, all organized baseball players from Little League to the Professional ranks do). Take a look at any serious organized sport (e.g. baseball, football, basketball, hockey, tennis, soccer, racquetball, boxing, MMA, folkstyle/freestyle/Greco-Roman wrestling, track and field, swimming, gymnastics, motor racing, etc, etc) and thoroughly observe how the practitioners train and perfect their skills. EVERY sport and specialized skill set (e.g. firearm skills, military and law enforcement tactics, etc) all have and use isolation drills on the specific skills/attributes associated with the activity they want to improve. If we are being serious here, there is no sport around where you best learn/hone each specific skill involved by simply playing the game. That would be ludicrous because what are you basing your skill foundation on in the first place? I could go on and on with example after example to further reinforce my points but suffice it to say if you are serious about mastering any particular sport or skill, you must prepare (and prepare properly) if you want to become really proficient at it. So, bottom line, this means that to hone any one particular facet/attribute of a given sport/skill, you have to isolate the particular facet/attribute you want/need to improve upon. In terms of bkimble's specific question, improving punching power entails more than sparring to maximize his or anyone else's potential; "it" (i.e. punching power) needs to be isolated and drilled with this specific attribute in mind. Let me end this segment with a well-known adage referred to as the 7 P's: "Proper planning and preparation prevents piss poor performance."
I think that you will agree that boxing is different from almost any other sport. The reason I have pushed the sparring issue is because one can practise punching all day but it doesn't mean that they will land in a combat situation. One needs to simulate actual fight conditions. Once in sparring then you apply the concentrated training idea. If you want speed concentrate on speeed, If you want to be defensive concentrate on defense and if you want power concentrate on power. Your idea on the bag, isolating shots and concentrating on precision and power...Is this not more beneficial when done in actual combat situations? I find it a great idea to spar, cut down the number of shots and throw with intent. This will increase my knowledge of my own power and also increase the accuracy of such shots. When done over a period of time I feel the fighter becomes battle hardened and power increases. As Eddie Futch once said "Boxing is good training for Boxing."