Re: How long does it really take?
Well - I think what 20 year technique means is that you always will find room for improvement.
As far as Aikido never being useful - my experience tells me otherwise. It really does depend on your goals and the goals of the dojo you join. For the record no where that I have trained is the goal so focused on self defense that a year is enough but it is possible. I would say the same of all the other martial arts I have dabbled in.