My kickflip flipping speed is controlled by my popping foot.
I pop from the heel side of my tail unless backside flip or rotation.
If I want to land on a ledge I'm center of the tail. I don't do this much. Kick flip crooks have a high chance of folding me up now that I'm old. I have a tendency to land both wheels on top also I'm pushing into the ledge so I fold up.
I can flip my kickflip crazy fast if I line my toes up with the edge of my board. I think it's because when it pops the board starts to flip the other way giving me a harder flick.
All this might be bullshit idk.
I definitely know I prefer popping from center of heel side of the tail unless backside flips are the goal.
Interesting how people vary when it comes to kickflips- i pop my flips, fakie flips and half cab flips all with my toes/forefoot in the toeside pocket of the tail. I find it squares me up over the board better and keeps it straight relative to my shoulders.
I do my flips with slightly open shoulders though, so maybe the back foot position is compensation for that somehow.
Whatever works I guess.