I'm a relatively key employee, and I wouldn't feel right about leaving until my successor is in place and somewhat up to speed....
By the time I left, it was a toxic workplace. Our supervisor would walk through and do what we called "drive by shootings" sniping at us. At the same time we were keeping track of her work, and she was making more errors than any of us.
I worked in Contracts, and had a tremendous amount of customer interface on technical details. I was the only engineer in the group, and I heard that they had to hire 3 people to do my work.
Their loss.