Amazon

The largest channel and the least forgiving. Catalogue architecture, content, advertising and inventory health are a single system rather than four departments.

The work is unglamorous. Variation structure that reflects how people actually search. Search term isolation so that spend can be read rather than guessed at. Restock timing against lead times that move. Dispute and case handling. And the discipline to hold a bid when the dashboard is asking you to panic.

Brands that arrive expecting a marketing problem usually find an operations problem.