to control the twitchiness of ankle playing (assuming you use ankles for faster tempos), try to incorporate accents by implementing occasional leg power behind certain strokes, and actually stop paying attention to the fast ankle strokes - just let them happen while you focus on the accents.
For example, with a 16th note role on the double bass, leading with the right, accent every other right foot stroke with a little leg power. Think about those leg strokes being the *only* stroke, and the inbetween ankle strokes just being automatic free notes that happen on their own. IE, like the moeller stroke with the hands, you have a hard whipping stroke followed by an almost unavoidable bounce-tap - the free stroke... it didn't cost you any energy.
death metal tempos can be fast as fuck, and nobody can count rolls that fast, or listen and process what they're hearing fast enough. So, most the the drummers, myself included, incoporate a leg accent (or the ankle swivel) for time keeping. Which leads to relaxation, which then leads to big beater swings and more volume. I can play 250bpm rolls this way, without triggers, and tones of volume, on chain-driven pedals.
There are two approaches to accents, and I find one way easier than the other.
1) Think about playing accents only, and let the free in-between strokes happen on their own. Just focus on the leg accent. Keep your heels low as well, toes up, and use the ball of the foot as the contact point. An easy exercise to start is just pump the right leg on the pedal with quarter notes. Even do a count-in with the leg (like how death metal guys count in a blast beat with 4 strokes on the snare). Then without changing the leg motion at all, keep the pumping going while you add the ankles to every stroke (the leg stroke and the non-leg strokes). Again - think of moeller. Whip the hand with arm/wrist quarter notes, then start adding the inbetween up-taps to get the 8th notes. With double bass, I only do this with my lead leg. My left leg does it's own thing... sorta naturally does the death metal swivel.
2) the harder way is to focus on the ankles strokes and adding accents to them. Way harder because you're trying to analyze every single stroke.
The clip below changed my life because it taught me how to use my body to control and keep time with my double bass. At 1:55, you can see God pumping out accents on double bass rolls by putting his entire body into it. You might not have to mash them as hard as God does, because he uses maxed out heavy-duty springs with insane beater angles.
heel lifted up
