It depends on commercial pressure and on how overtime is compensated.

Early in my career our main customer put huge pressure on the company to fix bugs ASAP and we had to work 2 weeks flat out with overtime late every night plus over the weekend.

We managed to satisfy the customer AND I doubled my salary that month.

If it is a rare event then I have no issue with that. This has no negative effect on morale (it can even be a boost and improve team spirit), and in fact would be happy to get the opportunity.

It also helped that we had a good leader: our Director could not help on the debugging but made a point to stay with us and took charge of making sure we were kept well fed, paid for by the company, of course.

Leadership and compensation are key.