Agree with all of these, but especially

Implement to learn. You can go far with Spec-Driven Development, but the act of writing code surfaces decisions you hadn’t considered and makes your spec better. When code is cheap, implement to learn.

Rebuild often. Implement early and often to learn more. Fork and recode crazy thought experiments. Find out how far you can take feature. Of course, you want to iterate and compound your efforts, but cheap code means you can reconnoiter and reinvent in ways you never could.

There is basically 0 reason to try and learn entirely on a theoretical whiteboard, when you can learn (about your product, market, space) by doing way more effectively and way more grounded to reality