I find the double end bag is great for training reaction, accuracy, timing and co-ordination/hand speed The speed bag is the most useless piece of equipment in the gym, I never use them
Doesn't the speed bag help build shoulder endurance so that you can keep your hands up longer? I can keep the speed bag going with my eyes closed or while looking around at other things, too, so maybe the whole hand-eye-coordination thing is a myth. But I used to hit the speed bag for like 10 rounds straight just for fun. Around this time I rarely had trouble keeping my hands up while sparring even if I was gassed. These days I only do maybe 3-4 rounds of speed bag as a cool down, but it seems like my shoulders get tired quicker and I have a harder time keeping my hands up during the 3rd or 4th rounds of sparring. This may be due to other factors, such as different training routine, age, and/or heavier gloves than before, but I always thought maybe the speed bag had something to do with it too.
I feel neutral on this. I see that the speed bag has helped me improved a small amount but I certainly don't build a routine around it and the coach doesn't have us use it too much. Only thing I learned from him that made good sense about the bag is to be hitting it fast enough to try and simulate how fast the punches would be in a fight. When I started, I was doing a four count(four bounces) before hitting it which he said was too long in a fight, something about its 4-6 seconds where your standing there too long and now I'm doing a three count which is around 2-3 seconds.
It's definitely great for endurance gives the shoulders a good workout and tho I do agree with the legendary Cus D'Amato you can learn to do it blind folded, you can always pick up the pace. I usually start at a slower, regular 1-2-3 pace and for the final minute or so I'm just really trying to maintain it as fast /quick as I possibly can where instead of hearing the speedbag bounce 1-2-3, 1-2-3 you just hear 1-2, 1-2 because its bouncing so fast. Once you have the speedbag that fast I think it can get pretty challenging to do it blindfolded, unless your Floyd or Roy Jones! Those 2 were/ are especially apt at using the speedbag. Sure you might not need it, but it can help. I do feel abump in speed after 3 rounds or so. Also there are different sizes of speed bags which can make it a little more challenging.