I have been doing a lot of shooting these last few days, as I don't have to go to work anymore (hopefully for EVER!). I love YouTube!
Anyway. So far, I pretty much thought that tapering and band stretch are the only factors that have an impact on the band lifetime. No tapering, low stretch = many many shots, extreme tapering and stretch = very very few shots.
However that isn't the entire story.
My new through-the-insides shooter easily doubles the lifetime of a band vs. OTT frames. That's right. I got more than 150 shots from a 3:2 tapered band that I stretched to factor 6 (= as far as possible). That band would have lasted maybe 50 shots, 70 shots tops, on an OTT frame.
Then I cut a totally untapered bandset for an OTT shooter, same stretch. It broke after about 80 shots. However the important part is: It breaks at the pouch, just like the tapered bands do.
I now believe that one of the main reasons for the bands breaking at the pouch isn't the higher stretch. Maybe it is the impact of the bands when they snap back. The ITTF slingshot leads to way less violent hits because the don't have that hurling effect, but go straight back through the fork.
In other words: The OTT method leads to hits of the bands to the hard parts of the frame.
I now cut a loong bandset (40 cm active length), entirely untapered, 3cmx3cm, 2 bands per side. I attached it to the hand braced slingshot I made some time ago, but I "upholstered" the front with some thick leather.
Let's see how long these bands last!