This enlightening vid explains why tapered bands project faster than untapered ones and why if you hold for a few seconds and release the velocity is less than if you hold less time and release as in a "snap shot". The reason ishi the bands when stretched heat up and a warmer band snaps back faster than a cooler one. If you wait and hold and shoot the band cools off some and velocity lessens.
I pull a band back several times before I shoot to heat it up and release as fast as I can with accuracy in mind...not snap shooting, but as fast as I can and maintain accuracy. This gives me a flatter trajectory. If you hold longer on some shots than others, accuracy will suffer, you have to hold the same amount of time each shot to get the best consistency. I didn't know that until I watched this vid.