The multiplicity principle
An extremely important general principle of Jiu Jitsu is the multiplicity principle. It is seen in many different areas of the sport. The essential idea is this - FOR ANY GIVEN MOVE THERE WILL BE MANY LINES OF RESISTANCE SO IT IS EXTREMELY VALUABLE TO HAVE MULTIPLE VARIATIONS OF THAT MOVE TO BYPASS THAT RESISTANCE WITHOUT ABANDONING THE MOVE AS A WHOLE. The more variations you possess of your favorite moves and positions, the better you will be able to overcome the resistance your opponent offers. Here, Garry Tonon shows his usual masterful back control. Note how he makes use of many variations of leg position as he works the back position. If you limit yourself to one or two back positions it will be easy for experienced opponents to escape. When you can seamlessly switch from one leg configuration to another in response to resistance - using a multiplicity of rear mount leg variations to follow your opponents back you will be able to stay in good position long enough to get the submission breakthrough you seek. For all your favorite moves and positions - research the many subtle variations and configurations so that you can change the character of the move/position, but maintain the same position/move overall.