It goes without saying that the more complex a motor skill is the more repetitions are required to make the motor skill instinctive, smooth and efficient.
Case: The Hitchhiker Armlock Defense. To execute this particular escape you need to do three things simultaneously and very quicky: twist your arm and shoulder so that your thumb rotates to the floor, bridge your hips to the side, and run your feet away from your opponent in a half circle. This is a fairly complex movement!
How then do you become proficient at this or any technique? Drill it a lot! When you arrive early for a class grab someone, ask them to lightly apply the armbar, and practice this technique 5, 10, 15, or 50 times! Soon this escape will start working really well; you will use it in sparring all the time and eventually in competition.
Follow this pattern with all your techniques, the more complex a techique the more drilling will be required to make it muscle memory. Keep in mind that grappling skills are perishable so once you have mastered a technique remember to come back to drilling it again and again at future dates!