For some people working 50 hours per week is too much and for other people working 50 hours per week not bad at all.
Working 50 hours per week for 5 days a week is 10 hours per day working.
Some people only work 8 hours per day and some work 10 hours per day.
I used to work 10 hours per day on my job when I was working for other people and I never had any problems with it.
I didn't mind the work and 10 hours per day was not bad for me then.
I would say any hours of working over 50 hours per week can be bad.
In some people working 50 hours or more per week has been associated with increased alcohol and tobacco consumption, as well as unhealthy weight gain in men and depression in women.