The Weekly Fix
AI sprints through the first 80% of a feature, then crawls. Here is why the polish phase ambushes you, and how to plan for it instead.
AI nails 80% of a feature fast, then the last 20% takes five times as long.
The demo works in minutes. Then edge cases, error states, browser quirks, and integration glue eat your whole week. You keep telling yourself it is just one more hour.
The first 80% is patterns the model has seen ten thousand times. The last 20% is your specific edge cases and glue code that no model has seen exactly. It is not a skill issue, it is the shape of the work.
Plan for it. Block out 3x your gut estimate for the polish phase before you start. Treat 'make the happy path work' and 'handle everything that can go wrong' as two separate tasks with separate estimates. If you keep promising one more hour, you are estimating against the 80% phase.
I have a working happy path for [feature]. Before I call it done, list every edge case, error state, empty state, race condition, and integration failure mode this could hit in production. For each one, tell me how to reproduce it and the smallest change that handles it.
Full entry in the database: AI nails 80%, last 20% takes 5x longer →