How muscle memory can help you to be better at BJJ? We don't frequently think about this concept but in any sport it plays a big roll in your performance as an athlete. So let's think a little about how this works.
According to Jacoby, C. "Muscle memory is the ability of our mind to capture a particular activity or movement". In other words, muscle memory is when you repeat a particular activity over and over again and eventually this activity becomes natural for you. Then you can do it without being at 100% focused on it.
Talking about BJJ, when you learn a new technique the first time is always akwardm the second time too. After repeating it many times it starts getting easier to drill it. But, is that enough? The answer is no. After you perform a technique correctly, you have to repeat it a million times and try it during sparring. In that way you will be improving your muscle memory.
When you are a beginner you have much more work to do. All those exercises during the warm up that your coach makes you do, are the base of everything and if you repeat them properly, your game will improve faster. Sometimes you will find them useless, but I'm pretty sure that if you ask your coach the purpose of them, he will give you a good answer.
I encourage you to give more importance to this. Even though I am far from being an expert at BJJ, I have practiced other sports for long time. I know the importance of repeating the basic movements. Don't complain if you have to repeat an exercise many times, because the more you drill, the better you get.
Jacoby Christopher. (n.d.). What Is Muscle Memory? [Blog post]. Retrieved from http://www.healthguidance.org/entry/14351/1/What-Is-Muscle-Memory.html