For me the Sabbath is a recompile with bug fixes. When I'm GCing every night, at least someone can ring me in an emergency. The phone is off for Sabbath.

And I'm not joking about the bugfixes. A day off of _everything_ is a great way to reflect on the past six days, and to learn from them. I'm certain that my ostensibly-six-day-week is more productive than my seven-day-week ever was.