IOW, if you are doing this, it does not matter what you are doing afterwards.

You are assuming that a human's particular typing pattern is consistent, when the fact is that any number of ordinary events will render your assumption false (one or more fingers bandaged, sprained, whatever, or one hand occupied ATM).

This is not a hardware or software problem, and no amount of code, hardware, or cleverness will fix it; this is a fundamental mismatch between your assumption vs reality.