I said no, for other reasons, because right now I just can’t picture myself doing 9-hour days.
My company has done 4/10s and this scheme during summers past. I always want to say no, but then the idea of having an extra day off sounds really nice, so I do it. Halfway through the summer, I’m totally burnt out. The 9 hour days are definitely beter than the 10 hour days for every Friday off (or in my case, I prefer Monday).
That said, part of the problem is that I appreciate being able to work 9:30-6 on a daily basis. If I add hours, I do so in the morning, and I really don’t like waking up any earlier.