The only thing that prevents us from adding a full-time vibration is that the device itself has been not made to work continuously. It's basically a small electric engine with a little weight attached (unbalanced weight) and, in order to work, it needs to take some "rest" regularly (mainly to cool down and avoid the temperature of the engine itself to goo too high, also considering it's all enclosed in a plastic case). Another issue is the battery usage. A full vibration needs much more energy and it could drain the batteries.