You have your speed bag for some time, and you have learned the proper technique to hit it. Your fist moves like a mill and the bag flies so fast it can be hardly seen. Congratulation! You are the master the ball.
However, have you ever tried to use it not in the traditional way? Yes, there are many other techniques you can try to improve your speed, punches, combinations, and accuracy. Also, they may work your delts even better.
From the following video, you can learn how to hit the bag to improve your jabs, uppercuts, and hooks. It is worth to try these techniques for developing your skills, plus to make your workouts more interesting.