Every new model and you might as well chuck 90% of that knowledge in the bin.

Last Claude major version they released a blog post basically telling you to chuck away your Claude.md file and start again.

It was only 18 months ago when people were telling you to use ultrathink:

https://news.ycombinator.com/item?id=43739997

And then that went away about a year ago, and now it’s sort of back again but not quite as it was.