1. We choose 30 to keep Trainerbot small (it is the world's first ping pong robot that can fit in your backpack), so you can bring it to the any ping pong table near you and set it up in seconds. We tried all other ping pong robots out there, it is incredibly frustrating to carry them around. You do not want to experience that.
2. 99% of the people (including ourselves) we demo to need a rest after 30 shots or less into the drill. Otherwise, they got burned out from the drill and will start hitting low quality shots with incorrect form. This is really bad for Training.
Incase you really want to play more than 30 shots per drill, we will have ball extension add-ons ready for purchase after we ship all the Trainerbot units to our backers.