Comment by mrothroc

Everyone keeps saying 80/20 but that undersells what's going on. The last 20% isn't just hard. It's hard because of what happened during the first 80%.

When an agent takes a shortcut early on, the next step doesn't know it was a shortcut. It just builds on whatever it was handed. And then the step after that does the same thing. So by hour 80 you're sitting there trying to fix what looks like a UI bug and you realize the actual problem is three layers back. You're not doing the "hard 20%." You're paying interest on shortcuts you didn't even know were taken. (As I type this I'm having flashbacks to helping my kid build lego sets.)

The author figured this out by accident. He stopped prompting and opened Figma to design what he actually wanted. That's the move. He broke the chain before the next stage could build on it. The 100 hours is what it costs when you don't do that.