Writing JSON-LD structured data by hand, and when to stop (opens in new tab)

I maintain a handful of small marketing sites, and for years my structured-data workflow was embarrassing: copy a JSON-LD block from an old project, find-and-replace the values, paste it into the , and hope. It worked until it didn't — a trailing comma here, a wrong @type there, and the rich result silently disappears for a month before anyone notices. Structured data is one of those things that's easy to add and genuinely hard to add correctly. These are the notes I wish someone had ha...