Seems that varying rhythm is a popular way amongst classical musicians to work-up fast licks. For example, take a string of straight 16th couplets and dot the first note of each pair (and then move the dot to the second later on).
One reason it interests me is that it seems to more or less obey the ‘starting-fast’ rule. (Okay, guideline; there are no rules, I know, I know;)
Tried it a bit. Didn’t like it at all. It feels to me like if the passage is too fast as written, this doesn’t really help much. But again, it’s one of those tried-and-true things, so maybe it’s just me. Anyone have success with this approach?