I replied above, but I think there are some distinctions - 80 is probably the barely acceptable sustainable max you can work in a week. More importantly it's no

I replied above, but I think there are some distinctions - 80 is probably the barely acceptable sustainable max you can work in a week. More importantly it's not just working longer hours, extra hours need different mental management of that time to be effective, and I got those lessons from my professors during my PhD. Probably why I haven't burned out till now.