I don't get the confusion at all. Sal makes his directons really clear and precise, so I know his application process sounds extensive.
If you use Z1... all you do is apply Z1, then apply Z2 immediately over it. Let it dry (takes anywhere from 5 minutes to an hour, depending on weather) and wipe it off. Then wait 24 hours before applying another layer of Z2. The same goes for Klasse SG... you need to wait a day for it cure and crosslink. Some people apply 3 coats of SG back to back... you can do the same with Zaino, but each layer just soften the previous layer... like Klasse.
If you use ZFX... mix ZFX with Z2, apply it, and let it dry 5 minutes to an hour. Do the Zaino drying test to see if its dry...
To test if Z-2 is dry and ready to be removed, wipe your finger on a hazed section. It should immediately come off and leave a crytal clear finish. If it smears, it is still wet.
ZFX and thin coats help Zaino dry quicker. Then wipe it off. The maximum that you apply is 3 coats a day. So immediately after you wiped off your Zaino, you can start again. Apply, let dry, remove. Apply, let dry, remove.
If you do the ZFX method with Klasse... (apply and remove 3 layers a day), it would be different. ZFX immediately cures the polymer, and quickens drying time.
Lastly, lets not confuse DRY with CURE. DRYING is afer you apply the product, and you're waiting for it to dry (as in not be wet) before removal... 5 minutes to an hour depending on weather. CURE is after you remove the product, and it's the time when a polymer crosslinks and bonds with the paint. With ZFX, there is an instant cure time.
And with QD's, I don't use Z6 between coats. I only use it afterwards. And I wouldn't substitute Z6 with FI or any non-wax QD between coats. Pure synthetics require an oil-free surface.