As discussed before 10,000 techniques is an exaggeration but lets put it this way. Lets say as a white belt you're taught the front kick, side kick, round kick, back kick, reverse punch, jab punch, palm strike, and shuto strike. That's eight different techniques, a rather large selection. Than as a yellow belt, the next belt up, you're taught the crescent kick, foot sweep, knee kick, elbow strike, ridge hand, and finger strike, which brings the total techniques in your arsenal up to 14. Now, lets say out of all those techniques you choose to primarily focus on the front kick and the reverse punch. So you practice the front kick and the reverse punch both 10,000 times and you keep training primarily in those two techniques throughout your entire martial arts career. If you were to do so you would become extremely effective with the front kick and reverse punch and you wouldn't need much more. So while I believe its a good idea to focus on just a few techniques and to bring them to a level where you've mastered them and to get them as good as you possibly can, I also think its a good idea to know or at least be familiar with many different techniques. That way you will have a big pot to choose from and you will also be better at defending against such techniques.