That rule very much is like what zenoah wants.
I observed with a twin engined scale craft:
4 flips with choke on till first fire
8 flips with choke off till running
all this time and again, and very consistent over both engines.
This was the procedure the guy used. Mine is slightly different, but almost the same, and I use less flips. But then, I do not run zenoah's. Every engine has it's own procedure that works best.
The rear rotary ZDZ may be a bit different though. Not from experience, but from a technical vieuw, the procedure might differ a bit due to the added rotary drum, though I doubt it would meen a much different flip count.
Most of the time it is too lean idle settings and too little oil that cause hard starting, and the need for an electric starter.