In an economy of scarcity, a rare commodity like office space will be fought over tenaciously.
I have to admit that I’ve never had an issue finding office spaces on campus; at a previous university I had three separate offices, and presently enjoy two separate (and well furnished!) offices. I tend to work out of those spaces 6-7 days a week, 6-12 hours a day. In other words: I use the spaces that are provided to me.
That said, I’ve watched just how nasty office-space wars can become. Such conflicts aren’t something that I’d wish on my worst enemy, and the most aggravating aspect of most space conflicts is the sheer amount of unused office space. There’s nothing like seeing a war occur between a small group of people in a department for a coveted office space while 95% of the offices are unoccupied because graduate students and faculty alike refuse to come and work on campus.