Can't help you on whether to take a day off or two... though I'd tend to feel as you do about being consistent. We're a drive-in, so seasonal operations aren't really a problem.
I can tell you that, unless you're such a huge grosser the studios just can't pass you up, you won't get everything on a partial-week booking... assuming, that is, that you're talking about first-run. The more limited the release, the pickier the studios become. You might get some films, you won't get others... and there won't be a reliable pattern for any of it.
So... if you're first-run and it won't kill you, being open every night will eliminate some headaches with booking... though possibly not with your payroll!