Agreed that statistical power wasn't used to calculate how long test should have been run. I know statistical significance can be found earlier if you are "looking" for it, that is why I ran the simulations until it was found at least 10 times. (I know it is not the most scientific way, but I used it as a heuristic; I don't know how to use statistical power in case of MAB. Probably 'statistical power' concept is not valid at all for MAB. Need to study more.)