It actually depends on the firm's culture. Like the one I used to work with, they respect employees' families and most people could leave on time, like a 9-6 job except if upcoming deadlines (but most seniors or project managers would not stay as the tasks only involved with the levels below.)
My former coworker worked at SOM in SF before, he said it's expected that you have to stay late till midnight for a couple of days in a week, and you have to go back to the office every other Saturday. You could be fired if not. It's just the culture. So people worked in there for a couple of years and leave as they just entirely burn out.
For HOK in SF, most people stay till like 7 or 9 but some of them also came in late, which could still be 8 hrs of work afterall. In the team which worked on the airport, they actually stayed overnight for a tight deadline. My friend in another team left at like 8 and saw the airport team was working hard, then she saw them in the next morning at 7 something. She then said, "You guys are early." But one of them replied, "We stayed overnight." They left around lunch when they are done for the deadline.