Paradiddle-Diddle
R L R R L L L R L L R R
Practice tempo
What it teaches
Two alternating taps followed by TWO diddles, not one — six notes total, which shifts the balance of the phrase toward the double-stroke half. The specific skill is keeping both diddles identical to each other in volume and spacing, since a paradiddle-diddle exposes any inconsistency between the first diddle and the second far more obviously than the single paradiddle's one diddle does.
The common mistake
The second diddle comes out softer or rushed relative to the first, because single-paradiddle timing habits treat the second diddle here as an afterthought tacked onto the pattern; the correction is drilling just the two diddles back to back, alone, until they're indistinguishable, before adding the two alternating taps in front.
Tempo progression
Start at 66 BPM with all six notes evenly spaced; add 8 BPM once both diddles sound identical for a full minute. Most players keep both diddles matched through 130-150 BPM before the second one starts drifting.
Where it shows up
A common sticking for triplet-feel fills and 6/8 grooves, since the six-note shape maps naturally onto a triplet or 6/8 subdivision — the Single Paradiddle's four-note shape doesn't fit that meter nearly as cleanly.