Here's something nobody talks about...
When you find a winner, don't just reorder it. Find its cousins. I had a kitchen brand doing 60% ROI. Instead of just buying more, I searched Amazon for "frequently bought together" and "customers also viewed." Found 4 similar products from the same retailer. 3 of them hit 40%+ ROI. One winner turned into a whole category I now own. Your winners are telling you where to look. Are you listening?