Over my three years I will say that the situation has improved somewhat. In the 2009-2010 school year grades were to be completed a full 6 days before the "end" of the school year. In reality, once grades had been input, there was no reason for students to show up - so they didn't. In the 2010-2011 school year, we stil had four days between grades being due and the end of the year - a modest improvement but still difficult to pursue. This year, grades are due on the last day of school - even better for those of us wanting to give more chances (and more education) to our students.
Unfortunately, even this year there has been a breakdown of the rules as final exams were proctored over the course of the past week and if a student does not care about them (or has completed them), s/he may very well disregard the rules of the building and create headaches for the staff.
While I do not think that every suburban policy makes sense for urban school systems, I do believe that the end of year final exam schedule from Lower Merion has a lot of merit. When I attended LMHS as a teenager I found it relieving that we would have only two finals per day and that if we did not have to take a final, we did not have to come in. It made logical sense: do not force students to meander from classroom to classroom watching movies with teachers who have plenty of grading to do.
I am hoping that with increased autonomy in schools next year there can be more flexibility of these schedules. Perhaps the end of the year can be more organized and joyous so that it is no longer a headache for many of us.