I agree that keywords and niche play a huge role, and once you’re past a zRank of 4, that seems to matter more than the number itself. My experience with zRank has been a little different, though.
My main store dropped from a 7 to a 6 a few months ago, and even with daily listings, strong mockups, seasonal and trending designs, and fully optimized keyword titles, descriptions, and tags, it hasn’t gone back up. Meanwhile, my niche store which had zero sales in August went from a 5 to a 6. So both stores now sit at the same zRank, even though the main store gets far more views and consistent sales. That’s why I’ve always felt zRank doesn’t respond to sales.
A top seller once shared a few things that supposedly help: completing your profile with a clear banner and logo, organizing collections, deleting or hiding items that never get views, and promoting externally through places like Pinterest, facebook. I’ve done all of that, and it hasn’t made much difference for me personally, but it might help someone else.
For items with zero views, I’ve heard different approaches. Some delete them, some hide them, and I hide and recreate the listing with a new keyword title, description, tags, and a fresh mockup. Zero views are often just an indexing glitch, so recreating can sometimes give the product a clean start. I’ve tried all three methods, and none of them have noticeably changed my zRank, but it may help if the original listing never indexed properly.
The only consistent pattern I’ve seen is that niche stores seem easier for the algorithm to understand. My main store is more like a department store with something for everyone, and I suspect that variety makes zRank harder to predict.
Zazzle says a zRank of 4 or higher is what’s needed for marketplace visibility, and that’s been true for me everything still shows up in search. Higher zRanks are nice to see, but sales history, niche clarity, and strong SEO seem to matter more once you’re past that threshold.