That's my impression from my job, which involves a "private, real-world"[1] codebase.

You need to explicitly tell the LLM what to take into account when generating code or it will miss things. And that's with months of saved memories.

Where it fails is on plugging business logic in. Tell it to generate a new piece of UI and it will do that fine.

My guess is the 10x success stories are for from scratch applications where 80% of the code is boilerplate and self contained modules. And no one comes back and tells you maintenance dropped the productivity improvement to 2x.

Btw since it's mentioned a couple times in the comments: the Claude Team and Enterprise subscriptions do not train on or retain your code by default. Apparently the promises were good enough for my employer and their customers.

[1] By the way, real-world smells of LLM generation. Normal people write "real world".