Practice so that the Z grip with an extra packet doesn't require you to hesitate at all.
Extend your fingers more during the scissor cuts. Hey, Cardistry is hard, so when you can do something, FLAUNT IT LIKE KIM K!
It genuinely is one of those moves where the entire beauty is it's speed (unlike displays, aerials or even several packet cuts). So keep practising till it becomes fast (and smooth, of course). Mine isn't as good as Eliot's yet, but I think you can easily speed up those times when you have to pivot the right hand packet around the left hand finger (because I could).
PS:- I like practising with my eyes closed. You end up memorising your hand positions which helps in being smooth.