Well. I'm torn on the 7-day thing. It's not all bad that new books keeps circulating to keep wait times down. Unfortunately many don't return books early, even if they have finished them, and I'm convinced many keep the books the whole 21 days whether needed or not.
But sure, it's a PIA if you happen to be able to check out a bunch at the same time!
(I actually have 7 days as my default lending period, and change it when I feel I might not make it in time.)