Certainly it is physically possible to dance those steps, so it can be done. It is non-standard however so it would not be allowed in many types of competition, but there is a very similar figure, see below.
There is also the matter of what you might dance after that step as there would be limited choice in normal quickstep starting with the man's left foot from that position.
A more typical follow from a spin turn would be a progressive chasse, which you may also know as the back half of a basic, and this leaves the man free to start the next figure with his right foot which offers more choice.
The progressive chasse is sometimes referred to as a "quarter turn to the left" . Technically that is incorrect as the quarter turn to the left is an older figure, less often dance these days but it may be acceptable in competition. For the lady the steps are essentially the same as 4-6 reverse turn, but the man steps back on his right foot as the lady steps forward, then pivots on his right heel and closes his left foot to his right foot without putting weight on it while the lady dances her side & close. The effect is thus very similar to 4-6 reverse turn.
I hope that helps. I've made the assumption that you are relatively new to learning quickstep. My apologies if that is wrong, but if I am correct I would suggest you rely on your teacher to build a routine for you and to develop it as you progress.
Thank you so much for your reply in details. It was a part of the routine that my new teacher gave us, I didn't feel comfortable to do it but I didn't want to offend him questioning the step. The rolling promenade step follows after the 4-6 reverse step (my teacher call it) Regarding the quarter turn to the left step, my teacher also calls it by that name for progressive chasse and I don't feel comfortable...
Social Dancer is correct. It might be worth pointing out that it is possible after a Natural Spin Turn to do a Heel Pull turning to face diagonal to the centre which leaves the Left Foot free to do any Reverse Movement
Hi Aispark Never be afraid to ask your teacher to clarify something you don't understand. Asking questions is an important part of learning. Of course, don't ask the question in an aggressive or challenging way. A simple "would you please go through that again?, i don't quite understand...." or similar. Don't try "i went to teacher X and he told me something different". Even if this is true! Good teachers actually enjoy questions because it gives them the opportunity to assess the pupil's abilities or understanding, and thus provide better learning for them.
Aispark. I would say that the answer is No to can we do 4 5 6 of a Reverse Turn after the Natural Spin Turn like in the Waltz. For a start we have 28 bpm opposed to 50 bpm. The Waltz is commence to rise at the end of step one, continue to rise on two and three. Lower vertically at the end of three. This in the Quickstep with the speed of the music without a drastic change in the footwork would not be feasible. Example the third step would have to be flat to the floor.
Of course "4 - 6 of Rev. Turn" is possible. In former technique it was the second half of the Quarter Turn including man's "Heel Pivot", for less advanced dancers changed to a "Waltz step" as described above. We could call it "Chasse Rev. Turn" (ISTD "Moore"-Ballroom Techn.) with man doing lady's steps and lady doing man's steps. It is important that the man is leading this "side - close" different to a Progressive Chasse: - He does a very small side step - Has no "body turns less" at the closing - lowers e/o 3 to start the following part with heel and CBM (I say "kind of Tango-Feeling" - nearly CBMP) so that his left leg is very close to the outside of lady's right leg as the 1st step of the following figure. So overall he has to stop lady's progression.
The question was . Can we do a 4-6 of a Reverse Turn after the Natural Spin Turn in Quickstep like in the Waltz. 4-6 like in the Waltz would have to be completely flat S.Q.Q. Might as well do a Heel Pull. Could do a Slip Pivot instead. In either case we are introducing another figure after the Spin Turn to do the Chasse Reverse Turn. I think we would find that a Slip Pivot would be more spectacular and in keeping with the Quickstep to keep it moving.