How the drill works
Keypad Blitz strips out formatting entirely. There are no dollar signs, decimals or dashes — just a run of random digits whose length is fixed by your difficulty, from two digits at Beginner up to six at Expert. Every string is the same length within a session, which makes it unusually good for building rhythm.
Skills you are practicing
Consistent stroke length is the underlying skill here. When every target is the same size, you can feel the beat of your own keying and hear when a finger hesitates. That hesitation is almost always a reach to the top or bottom row rather than the home row of 4, 5 and 6.
Try to key the whole string as a single burst followed by Enter, rather than digit-pause-digit. Blitz sessions of two or three minutes tend to be more useful than long ones — the point is intensity, not endurance.