Hi Duffy
I also use the Zaino range, AIO then covered with ZFX'd Z2, left alone for a few hours to cure then Z-CS applied smoothly and left to cure without buffing off.
I wash fortnightly now using a Gilmour Foamaster and Megs Hyper Wash, about half a CM in the bottom of the bottle topped up with warm water. This seems to just wash the car and leave the LSP pretty much intact.
Guernsey winters are a lot less harsh than Glasgows, but the Zaino CS states on the bottle that it can last up to 9 months, and if you are washing and "topping up" with the Z8 regularily you should be well covered.