Well... I have been boxing for a while... and I think you can increase your speed hitting the speed bag.. there are many different ways to hit it... and use your head... mind is the most important thing... You can do anything if you focus... work on techniques and take it slowly... learn how to balance and use your weight properly until you fill like your power is there.. because if your weight is not there... then your punch will be weak and your speed... learn how too move your feet to set up for your next punch.. it will make you faster... Real Talk...

Also remember to twist your hips while punching cause it gives you more momentum.

Hm the speed bag has come up quite a lot, well the speed bag it good for rhythm and timing for punches also it increases your shoulder strength when you hold up your arms to keep hitting the bag.

But the speed bag does have its flaws, if you keep practicing it it will mess up your technique unless you hit the speed bag with a punching fist.