Some mastery drills that can be done are practicing being pushed against a wall, either with your back to the wall and facing the wall. Another good one is a side choke defense. Work it using both sides because you never know which way your attacker will come from. Once you master the technique then closeups your eyes and have your training partner attack you. This way you have to react to which side he or she is attacking you and respond accordingly. Another drill I like to use is, again closing my eyes, have my training partner,while holding pads or mitts ( depending on the technique we’re working on) make light contact on my back, shoulder, front etc, and I have to immediately open my eyes and react utilizing the proper technique.