Well, as you probably know, nothing with fillers is ever going to be permanent. However, the fillers in Z5 last much longer than most, from my experience. I think as the Z5 gradually deteriorates from the surface, the fillers do as well. And, of course, there is always the possibility of introducing new marring in the Z layer(s) afterwards.
Z is NOT the kind of product where the fillers wash away after a week, but the protection remains. The fillers are part of the chemistry and will last as long as the Z does.
I believe most other filling-type products rely on heavy oils, which are easily washed away. Zaino contains no such oils, and therefore is a much more durable filling product.
Hope this helps
Mike