How to hit walls of death without vibrating

[DossarLX ODI]

Ok so that is almost 250 BPM 16ths. Basically, overlay setup is when you have a keyboard that is sensitive enough to allow for two fingers to hit on the same key without having to entirely lift up your finger.

When OWA played Crowdpleaser for example, he did a one-hand trill with two fingers on his right key and did the same for the left key. This means it's basically two 16th trills at 240 BPM on each hand, but only using two keys.

Similarly, it could be done for a roll except using four fingers on each hand, with two fingers for one button. It makes sense the max would be around 250 if it's utilizing one hand trilling like that.