We're working with a weekly deployment schedule, Friday morning 3-330AM, so we can catch any bugs on Friday before the weekend. Why do you or your company deploy when you do?
We never deploy on a Friday unless it's a truly trivial change or a fix to a critical bug. That way we can avoid staying late on Friday or coming in over the weekend.
Other than that, we deploy whenever we have something deploy-ready, tho usually not last thing before packing up for the evening.