Stop running Amazon PPC on all your ASIN variations. Here is the strict logic you need to apply to your catalog:
Most sellers blur the lines between Hero SKU and secondary variants. Default lazy approach is dumping all child variants in every ad group OR advertisnig every child SKU on the same keywrods.
\- Prioritize the Hero SKU for Head Search Terms: Your highest-converting, most universally appealing variation should take the lion’s share of major volume keywords. If you sell bedding, your Hero SKU gets targeted on "Silk bedsheets."
\- Map Variants to Specific Intent: Stop bidding your Hero SKU on long-tail, hyper-specific searches if a variant matches it perfectly. Size and color variants should only be targeted on exact intent. "Queen silk bedsheet" goes directly to the Queen variant.
\- The Margin Exception: If you are currently targeting multiple variants on the same keywords and the unit economics work, leave it alone. Data beats theory.
However, if your Total Advertising Cost of Sales (TACoS) is creeping up at the parent level, the leak is almost always at the variation level.
When was the last time you isolated your TACoS and search term overlap down to the specific child ASIN?