I mentioned in an earlier post that I'd been practising along with Sharath's primary series DVD recently and that I was struck by the economy of his vinyasa. Jumping back in half lotus is an example in point. Didn't take as long as I thought it would to get the hang of it. I tend to bring my trailing leg back so my toes are just behind my arm as I lift up but before I begin to tilt forward and swing back through. Need to kick up a little higher to give you time to unfold the lotus.
In Primary you can use this in
Ardha baddha Padma Paschimottanasana A
Marichiyasana B and D
And in intermediate
Supta Urdhva pada vajrasana