Well, what works for you, works for you. It is worth considering the 'placebo effect' with all these things though- if a bottle 'tells' you its contents will improve your performance, then you train harder by default if you believe it, but we all have our psychological 'boosts' whatever they may be, and an enhancement of the mind is as valid as an enhancement of the physiology, so if you are happy and percieve benefit, then it is a worthwhile investment for you. Others results may vary, and that goes for any and all supplements.
Don't let the door hit ya' where the good lord split ya'