This is just my two cents, the only reason I am commenting is that the Electric Chair/Vaprozer is my #1 submission. I have yet to fully understand the whip up, whip down, suck, uppercut, duck all that shit.
Honestely I have never been too concerned with DOUBLE undercooks. All that I really need is the same-side undertook. Once I have lockdown and that same-side undertook, its game on. What I do is roll them back and forth between dogfight/back-take threat, and electric chair threat. If they have that far side undertook? I'm already transitioning to the back. If I have that same-side undertook I am climbing on to their back (or "throwing" them so hard that they are forced to post on the opposite knee.) I threaten the back-take with that same-side undertook so hard that the far side undertook does not even matter. Its almost always curling the back of the knee in preparation for an electric chair, regardless if they have a far-side undertook or not.
If this makes no sense please disregard. In short, Im rarely concerned with the far-side undertook and Electric Chairs are my best game. Its that same-side undertook I find incredibly essential. Dudes in my gym fight me for that shit IN my lockdown.