Store brands have improved enough that the "always inferior" assumption no longer holds for most categories - but it isn't universally true either, and knowing which categories actually differ matters more than a blanket rule either way.
Simple, standardized products - basic pantry staples, over-the-counter medication with the same active ingredient, plain household goods - rarely differ meaningfully between store brand and name brand, since both often come from similar manufacturing processes.
Products where formulation, taste, or manufacturing precision genuinely varies - certain skincare, specialty foods, precision tools - are where the name brand's extra cost more often reflects a real quality difference.
Switching an entire shopping list to store brand at once makes it hard to tell which swaps actually mattered. Testing one category, comparing directly, and deciding from there builds a more accurate personal picture than following a general rule.