Im a bit confused by this. Do professional groomers NOT always use blade guards to get the desired length? Im under the impression that if you do not use a guard, regardless of blade size, you'll wind up with a short coat, or shave. If they do not use the guard (snap on comb), how do they get the length to stay on the coat...without scissoring? Please fill me in on this. Also, I read that blade guards are best used with a #40 - #50 blade, any truth in that?