Lousy title, I apologize, I have trouble with titles at times. The question really is how frequently and how long do you need to practice martial arts techniques before they are committed to motor memory? In other words, how long before they become automatic, techniques you use without thinking about them, your attacked and you respond with techniques without thinking about them. Bold lettering is by accident.
From what I recall from my memory there is no time an sich.
Depends on your age, the speed at which your brain adepts and so much other factors.
Muscle memory is nothing more than the adaptation of your brain to carry out movements with better accuracy & faster execution. There is no memory within the muscle, it's a brain facilitation to movement. As the word says it: plus facile (easier).
First you have the rudamentary movement which is hard to learn (because you don't know which muscle must contract at which time, so massive energy use), once this base is build, your brain starts memorizing the specific movement into a motorprogram. These are stored in the post central gyrus (and some other parts as well).
The more you repeat the movement, the easier the program is picked up in the brain and because of an increased amount of acetylcholine the program is executed in a better way, saving up energy (because not all the muscles contract anymore). The speed goes up as well.
not matter how much you repeat the process, it will keep improving. Even when you think that you've reached a certain point, it will keep improving in speed, accessability and better performance.
Feedback (positive feedback, aka constructive feedback) actually speeds up the proces. That's why feedback is so important.
This is the same principle that is being used on patients who lost motorcontrol of their arms aswell. For instance to learn how to write again.
So just keep on doing it.
edit: that is why it is so important to train with a teacher when you begin instead of out of a booklet. If you got the base wrong, it's very hard to unlearn it. As the program is made.