ATR, the one-foot flick in the 2BR works because of the propulsion, rotation, drive that it provides to the hip & eventually the shoulder (of the spearing hand). This is done in a cross or diagonal posture.
A couple of TI practitioner cited, that doing your kind, because they've experimented (or similarly, they started the 2BK this way) with the form that you do, negated the overall effect desired that they were unable to develop the propulsive force that would move/rotate/drive the hips.
When I do my 2BK version with the one-foot flick, I noted that the other foot, though drafting along was moving up-down, providing a sort of counter-balance with the foot-flicking foot, if you get what I am trying to convey. Couldn't you be doing the same?
I knew that the 2BK - with foot-flick (I initially described it as foot-driver, in my earlier threads) - was working the way it should (for me at least) was because of the following:
a. it produced the propulsion to initiate the hip-drive
b. it produced the glide to be able to spear entry the hand quite "gracefully" (if you know what I mean)
c. it produced a sense of ease, satisfaction, to be able to be moving forward, with seemingly effortless manner (can't seem to pin down the right word)
Combined with the energy savings from the marionette hands, relaxed head position, patient hands (though I still have to do more focus on this), I felt that I still had enough "gas" to go on and on.
The breakthrough for me was as Vol described it when I exaggerated and used the scissors kick, focussing on just the foot driver.
Also, I noted doing the superman with gentle flutter before doing the 2BK whole stroke, helps.
Am still in the stage of fine tuning my foot-flick's amplitude, the spear entry noise level still has to be reduced (I need to look for the correct angle of attack at different speeds), oh, so many other focal points to iron out.
But we'll get there someday - developing endurance, being able to do the right stroke repeatedly - as CEO TL said, it may take time before we feel that we're there.
ATReides, try and try, experiment, focus...