So what level of crunch is ok? Honest question. Overtime is a part of work sometimes and I don't think that's too much. But when does overtime turn into crunch?
So this is complicated. Even in well organized projects, a very momentary crunch can occur. Usually these are just 1-2 day affairs and usually the result of a live site incident or other breaking change.
In these cases, it important to either compensate the individuals on call to handle the issues or provide time off after the fact to recover.
A good industry example of this is Google. Any employees at Google who are in an on call rotation can only be on call once every 8 weeks at most. In exchange for agreeing to be on call, they receive a significant pay bump, around 15% of an already huge salary, for doing so.
One thing people fail to understand is how counter-productive crunch time and long hours is if it extends for longer than about 1 week.
Part of why I became a PM was because I was sick of seeing tech workers getting burned out. It didn't take long. After just 1-2 weeks of crunch, most had lost all benefits of crunching.
Sure, you can work your team 50-60 hours a week. Once you do for more than a couple of weeks, productivity plummets. After just a couple weeks, if you have tracked your velocity properly, you will rapidly see worker productivity drop below what you were previously getting out of them in 40 hour weeks. This often causes teams to crunch even harder and add weekend work. This once again causes a momentary bump in productivity followed by an even deeper drop just a couple weeks later.
By the team you finally ship, you have screwed your organization. You will lose employees. This is a permanent loss of tribal knowledge and in many cases key motivational figures throughout the organization. The good people will go find a more sane job. You will mainly retain the employees that cannot find another job or are afraid to try to do so.
For those that stick around, it can take months for them to recover from a crunch, even if you give bonus time off.
Even worse, crunch can easily become an assumed part of culture. Employees will start to plan to do work during crunch. Saying things like "We can just handle that in crunch" or "Don't worry that you are running late. You can catch up during crunch.".
Anyone who thinks crunch is OK, unavoidable, or even a good part of "DNA" or culture is just wrong. It's harder to avoid in new organizations, but once you have a good idea of velocity of your individual team members as well as the organization as a whole, it should not be that hard to avoid.