He is a friend, but if he gave that advice without any additional context, it's misguided. When you regurgitate that advice without any additional context, you are misguiding others. He's also wrong on muscle memory. Think about all the things you do without thinking about it: type, chew, operate the pedals on a vehicle, ride a bike, play a musical instrument, etc. indexing a pistol on the draw is no different. Do it enough that it becomes subconscious and you will do it better, faster, and more consistent.