Hadn't realised that IE updates more than just the browser, but it does make sense that it also updates Windows Explorer now that you mention it. But then again, I don't use Windows Explorer either.

I do keep Windows up to date otherwise, but not on automatic updates. I check the updates roughly once a month and get the critical ones, and scan the recommended ones for anything I could need. There's a lot there I haven't bothered with, and my system works perfectly fine as far as I can tell.