The paradiddle-diddle is six notes — R L R R L L — a paradiddle followed by one extra double. In 6/8 it lays out as one rep per bar, beamed naturally in two groups of three: R L R and R L L. The downbeat is the lead-hand single; the closing double sits on the back half of the bar.
What makes it distinct from its six-note neighbors is the texture. The double paradiddle is single-heavy (four singles, one double); the six-stroke roll is double-heavy (one single, two doubles, one single); the paradiddle-diddle splits the difference (two singles, two doubles). It feels like a paradiddle that overstays its welcome — and that's exactly what makes it useful for fills, because the extra double creates a natural place for the lead hand to swap.
Played with R-lead throughout (R L R R L L · R L R R L L), the closing LL hands the lead back to the right naturally, so the rudiment is self-perpetuating with one fixed lead. That's the form most drummers use exclusively. Exercise 4 inverts that: forcing the lead to alternate between bars, which surfaces any imbalance between hands.
Exercises
Sticking: R L R R L L · R L R R L L. Same R-lead each bar — the closing LL flips the hands back to R for the next downbeat automatically. Only one accent per bar (the lead R). Don't worry about the diddles being perfectly even yet; just learn the shape and let the closing LL hand off cleanly.
Same sticking as Ex 1, accents stripped away. The work here is balance: every note must sound the same volume. Pay particular attention to the second note of each diddle — the second R of the RR, the second L of the LL. Those are the four notes that fail first under tempo. If the bar starts to sound like R L R-R-L_l (the second L mouse-quiet), slow down.
Accent only on the leading R of each bar. Five quiet notes follow each accent — the first half of the paradiddle (L R) plus the entire closing diddle pair (R L L). It's tempting to lean into the second R of the RR diddle because it shares a hand with the loud lead; resist that. Both R's of the diddle are quiet.
Bar 1: R L R R L L. Bar 2: L R L L R R — the mirror. This forces the lead to alternate between bars, which is not the natural form (the natural form has the same lead repeat indefinitely). Why train the unnatural version? Because it forces both hands to play the lead role, exposing weakness on the off-side. Harder to keep clean; the payoff is a more balanced rudiment.