Likewise. I've worked at startups at it was a rare occasion my boss could convince me to stay past 6pm. When we were working on a big release and the work wasn't getting done fast enough or his liking the solution wasn't for me to work extra hours - it was to tell him, "you need to hire another developer to work with me". There are laws to protect you from being worked into the ground and at the end of the day, if you're a developer, finding another one isn't particularly hard whether it's at a startup or a big corp. It's a job, not a lifestyle. Work 9-6 and get out of there.
Of course, what I meant was that if your employer is forcing you to work 60 hour weeks you shouldn't fear threatening to quit as if you have to follow through on your threat it's unlikely you will be without employment for long. Unfortunately, in a lot of industries people don't have this luxury.
I think if you have to switch 4 times a year, either you're exceptionally unlucky or exceptionally bad at evaluating jobs for their effect on your personal fulfillment/happiness.
