Razorback's summer hours are June / July / August. We are open five days a week (Wed - Sun). We tried being open on Mondays last year (since many of the holidays fall on Monday throughout the year), but we were getting very little business. Wednesdays have been VERY good for us, much better than Mondays.
We are about to transition back to "Winter" hours - Friday / Sat / Sun, because, as has already been noted, attendance falls of dramatically once school starts back (Monday, August 18th for us), and the school field trip season doesn't really kick off until March/April.
I foresee a time in the future when we will be open five days a week, all year 'round. We started out three years ago with Sat/Sun only during the winter, but Fridays have been good for us.
Still lots of work to be done when we are "closed". New exhibits to research and put together, chipping and painting and other maintenance. We're still getting After Battery ready for our eventual overnight program, etc. We'll load our three MK14s sometime in October, for example.
Oh, we also actually take some time "off". Of course, my time "off" usually involves a trip to another museum...