That's the interesting thing about Zaino. It lasts so long that many of us fanatics can't keep our hands off the finish for that long. However, every time I try to out do the Z-5 and Z-8 thing, nothing seems to enhance the look. I really didn't find that CS was worth the money or the effort. Then after six months I tried another layer of Z-5 and guess what? It didn't need it and it didn't do much. The stuff is truly awesome. I think you should stay with what you've got unless you're unhappy with it.
Patrick