I dont think 6xBB is necessarily a bad raise, as long as you're doing it with every hand that you raise pre flop...If you raise KQs pre flop in position, you have to make sure that is consistent, or people will pick up on it. Raise only 4x with KQ, then 6x with AA and wind up showing both down...an observant player is going to come over the top of you next time you only raise 4x BB knowing you arent holding AA/KK and drivign you off it. Thats why most people will recommend a standard pre flop raise size, or to vary it as randomlly as you can.