Whatever your interval duration is you'll get a "reflex speed" of average double that: Shannon-Nyquist sampling theorem. So if you want to play at a 100ms reaction speed sample every 50ms or less.

4ms caps your max reflex time at, say, 10ms. Or about 16x faster than your average human [https://www.biology.usu.edu/files/uploads/Courses/Biology%20...]

I'm no expert in sampling. Any bona fide experts want to weigh in? That works ! :)