The "Markedly Different things" in each bin was a big Amazon Warehouse advance in warehousing. Traditionally - things that were "alike" were put on shelves/bins - but (according to Amazon) it was far more efficient for pickers (at least back in the day - may have changed since then) to have random things on shelves located near each other to allow for equal access to popular items by pickers.
Yeah, my emphasis should have been on _successfully_ training the folks doing stowing, in such a way that they actually work that way.