Agreed. However:
That's a factor of 3 to 5 improvement reported on here. If you keep stacking these kinds of improvements, you end up at month to minutes pretty quickly.
Compounding like this ignores fundamental friction. You can attempt a huge document processing factory but quality will go into the toilet.
The AI can't make a reliable judgement, so now you have to hire 3x to 5x more to make those judgements if you have the documents coming in at 3x to 5x faster. Or you'll have one severely overworked lawyer. It's the same problem developers have with thousands of AI generated PRs. Just because you speed up one thing doesn't mean the whole system works faster, and yes a human really does need to be in the loop or you end up with even bigger problems, and lawsuits.
That doesn't take into account dependencies between tasks, where bottlenecks can happen. In any case, Amdahl's law applies regarding what kind of speedup you can get in such a case.