Working long hours is sometimes a necessary evil, but if you're doing it regularly as a salaried employee, you're basically working for nothing. Jason James writes on We Are a Mammoth the many ways working long hours is bad.
First, after 40 hours a week, every additional hour doesn't add additional dollars into your bank account (unless you're one of the lucky people to be paid overtime):
Salaried employees are salaried to allow the company some flexibility. This flexibility is often compensated for, but compensated in a 41-50 hours a week sort of way, not an 80 hours a week sort of way.
Working more than you're compensated for simply devalues your work and your time. James points out several other problems with the 75+ hour/week mindset: it's unsustainable for the company, unhealthy and unsustainable for the employees (and can result in depression), it's a sign of poor leadership and poor project management, and it doesn't result in better work.
Maybe it's impossible to get to the ideal 25 hours a week structure, but if it's you having a hard time going home on time, it's time to learn how to stop working so much (unless you like working for peanuts or for free).
if you are going to put in the extra hours, make sure it's on your own terms. And if some place or some job is making you feel like long hours "come with the territory" just know they are misleading you to their benefit, and you can find a better situation with some extra effort.
What Long Hours Really Mean [We Are a Mammoth]