When Big Law attorneys talk about the maximum amount of hours they could bill annually without sacrificing sleep, family time, exercise and general well-being, the figure of 1,800 hours comes up a lot.

It's what many large firms used to ask of their attorneys, according to one managing partner, until billing expectations began rising with the tech boom of the 1990s. It's the maximum amount of work most people can do without hurting their physical or mental health, according to scientific research, and it's the official recommendation of two state bar associations. It's an honest 10-hour workday (not counting the commute) and a five-day work week. And according to a recent American Lawyer survey of mental health at law firms, it's something plenty of lawyers would take a pay cut in order to attain.