It varies a bit by field. It's more common in software to have irregular working hours with periodic "crunch time". I suspect part of this is just down to tech

It varies a bit by field. It's more common in software to have irregular working hours with periodic "crunch time". I suspect part of this is just down to tech companies not being all that well managed on average, so they often mispredict staffing needs. Some of it may also be a culture that considers that the norm, or at least acceptable, so it's self-reinforcing. It's particularly prevalent in videogame companies. At large engineering firms outside of software it's less typical. If you're an engineer at Lockheed, Exxon, or Dupont, the expectation is that you'll work a regular 40-hour week, barring really unusual situations. Many people even carpool to & from work, so you have relatively little flexibility in staying late even if you were tempted to: if your carpool leaves at 4pm each day, you leave at 4pm.