i guess i should've been more clear, but i meant after the followup.
like, sometimes you don't react quickly enough or you miss the jump input because you're still in the active frames of the followup, and the opponent goes a little bit further (due to the tumble/whatever you call it effect) than he would have been had you timed it right.
i rarely use 6D (or any counter, really) outside of instant blocking into it and punishing block strings, so when i do use it on reaction i often end up having to double jump.
although walking forward and single jumping would work as well, but that may screw up your positioning depending on who you're facing.