Even with checking, it turns a 3 day brief into a 4 hour brief.
And, part of the process is to do some research first, find the key cases, and the briefs of better lawyers on the same issue, and include them in the context.
And the time savings are passed onto the clients?
Doubtful, because GP has to pay the subscription fees for all the LLMs he's employing. I know ChatGPT pro for deep research is $200/month, Gemini deep research is (I think) $20/month for now, Claude pro is $20/month. Cheap compared to lawyer rates but I doubt they'll stay cheap.
LexisNexis rates vary quite a lot but $200/month for a small law firm is in the ballpark.