I don't think 10-20 is necessary. As far as offensive techinques, you can be competent with a jab, cross, and uppercut. There's nothing in the grappling realm that is as versatile as those three punches, and little that is as easy to become competent with as the first two (the uppercut takes a bit more). Add a hook, and you're still only up to 4 techniques. Learn to cover (let's count that as a technique) and one basic approach to footwork (let's call that one) and now you're up to 8, counting generously. And you can do a lot with just that. Will it cover everything? No. But it can get the job done.just limits technique s doesn5 get you their faster, if you limit them to one, they will learn it quickly, buts its combat efficiency will be somewhat limit. you clearly have to have sufficient technique to fight and that's going to be in the order of 10 to 20 no matter what you learn