According to the standard theories, unreasonable work weeks are self-defeating…because workers get tired or demand high overtime rates or simply rebel. However, according to a newer model, some businesses manage to develop what economists call a 'rat-race equilibrium.' The rat-race occurs when managers use a willingness to work long hours as a sign of some tangible yet much-desired quality that merits promotion.

The researchers pointed out that partnerships in the large law firms they studied are elite positions in the legal profession, offering high earnings and opportunities for leadership in the profession at large. Thus, an effect of the rat-race equilibrium is to reduce access to powerful positions for those unwilling to work excess hours early in their careers.