Partly it depends on the business cycle. From 2003 to late 2008 I was offered far more work than I could accept, so I felt free to turn down whatever I wanted to, confident there would be more. And in that situation, I preferred to overwork for stretches, and then claim whole months for personal projects. That was a personal preference of mine.
Since the onset of the recession, picking up work has taken slightly more effort, though I've been lucky in that corporations seem more interested now in developing with some of the web frameworks that became available for PHP, and I have a track record with frameworks like Symfony.