Graduate school has the reputation of being a time sinkhole: 40 to 80 hours a week spent on work despite a 20-hour stipend, Friday nights spent analyzing data rather than going out. To a certain extent, this is true, although I personally don't push my time much past 40 (of real work, not of browsing the Internet from my office). The upside to the time sinkhole is that it doesn't really matter when you work. My advisor doesn't care if I show up to the office at 9 a.m. or at all. There are offices out there that work 10/4, or take every other Friday off, or treat Saturdays as required work time. My schedule can do any of these, depending on my need. It took my advisor three days to notice that my computer clock was accidentally set 12 hours ahead; who notices whether a grad student sends emails at 3 in the morning, unless it's three in the morning tomorrow?
The upshot of this is that informing my advisor that I would unexpectedly be out of town and out of contact for a given weekend is more of a courtesy than a necessity. I'm not entirely sure it would be noticed if all emails went unanswered for a four-day weekend. Normally I'm not in a position to think about, let alone take advantage of, this flexibility. Impulsive trips to Cancun are not in the graduate student budget. At the moment, however, I have reasons to be thankful for this flexibility, as I plan to ditch research to attend my grandmother's memorial service.
My first semester as a TA, I received some advice about dealing with students who request extensions or make-up tests on the grounds of attending a grandparent's funeral. I can't remember exactly what the advice was - I think that it would be okay to request some proof of needing to attend a grandparent's funeral, but to accept a parent's funeral without question as if they're lying they're going to hell anyway. I never experienced the request from a teaching standpoint, although I did have to put up with any manner of other excuses. From a student standpoint, on the other hand, I got to make the request - my mother had a heart attack the last week of classes, so I missed an exam and a term paper deadline. I much appreciated the fact that the teacher didn't request proof. I even more appreciated that my advisor had no problems with me vanishing for a full four weeks; no one else in my family had that option.
Now again, I am the only member of my immediate family with an easy time attending this service. Three can't get out of work, the fourth is trying but has an even tighter budget than I do (yes, it's possible, especially if you have a house and two kids). Any time I think about leaving academia for the "real world", I think about how much more difficult it would be to drop everything; professors can cancel class, or call for guest lectures, but in a business there are bosses to appease and hourly wages to accrue. I have yet to decide whether this time sinkhole-flexibility trade-off would be worth it on a more permanent basis.