Here's what Lilia has to say about the weekly rhythm in her group: 

No meeting Friday is such a glorious way to end a week. My team of like 50 people (group policy, windows server) all have it blocked out in our calendars: twice a month no one can schedule a meeting with us. No design meetings to walk through how a typical IT Pro would interact with the new layout of a Group Policy homepage, no triage meetings to resolve bugs for Windows Server Update Services, no planning meetings for the latest beta, no 1:1's with your manager, nothing.

For a PM this is so stunningly different and crazy, it's almost impossible to imagine efficacy or productivity. It's like asking a lawyer to turn off his/her cell phone...ok, really, it's like asking anyone to turn off his/her cell phone but you get the point. It seems like there's no way I can get anything done that day, but it's meant to give us all time to actually get caught up, get stuff done, and have uninterrupted hours of productivity.

Or, as my manager put it, "Sometimes you gotta pick up the dry cleaning, y'know?"

After years of cleverly scheduling my classes to avoid Friday lectures (discussions were a little trickier to avoid) I'm glad that my work world has the notion of an empty Friday as well :)