> Lawyers bill by the hour. It is not in their interest to speed up what they do, because they only have so many clients.
This isn't how markets work.
If one lawyer starts doing 10x as much work in the same number of hours, then all the customers will move to that lawyer as soon as they find out, and the other lawyers will have to adapt to remain competitive.
Lawyers are extremely well-organized, and not surprisingly, know the law. They always have found ways to limit competition. (Why else would it be such a well-paid job?)
You forgot a crucial step, which is that the lawyer would have to charge less than the competition per person and make up the difference in volume
You don't go to the overworked lawyer if they still charge just as much as their competitors
And for a thought experiment - if a lawyer controls the pace of their work, why work at any reasonable speed? They could take the client's money and go picnic or something then put in 20 minutes at the end of the day.
Something is forcing them to put in long hours. It's the market.
I'd expect the market to only work like that for business clients. If I grabbed a person off the street and asked them how they'd evaluate a lawyer's productivity, I suspect they'd generally have no idea.
People are clearly hiring lawyers based on silly billboard ads, after all.