Suzy,
This is how I did all my cycles.
I was never down reged.
I can off a stim cycle with no embies and went straight back on to synarel and injections as soon as day 1 arrived. I got a BFP off that cycle.
I think it depends on different doctors and clinics and there time schedules allocated to treating IVF patients some like to do them in "Blocks" where they have scheduled days to do OPU's and Transfers.
Mine was pretty cruisey and followed my body rather than his time restraints.
I did do 8 FET cycles consect pretty hard emotionally, but the waiting was killing me more and the thought of not doing anything productive.
Good luck
Bec