I'd love to see what you come up with.
Inspired by two things - your comment in "Rotational Drills" about using them as warmups and your mantra of "don't judge success or failure until you've done five in a row", I developed my own sort of "warm-up" routine that I run through at the start of every session. I've been surprised at how quickly I've improved the individual skills.
In contrast to Club 38, where you do a pretty long pattern stringing together sometimes unrelated or out-of-progression elements, I'm doing quick repetitions of smaller skills - 20 reps of X, then 20 of Y, now back to X, but in the other direction, etc. It reminds me of penmanship in grade school - rather than writing a paragraph, I'm filling a whole page with a single letter.
The main advantage, at least for me, is I stay hyper-focused on refining each skill in its turn. Also, I feel like it's more directly building muscle memory for each skill.