I do it for sizes less than 10KB (completely arbitrary) for most websites because the fact of the matter is that most websites don't get repeat visits often, an

I do it for sizes less than 10KB (completely arbitrary) for most websites because the fact of the matter is that most websites don't get repeat visits often, and visitors rarely visit more than the page/article they arrived at. There's no point making all visitors cache a CSS file when only a tiny minority will need it. Note that I live in the middle of the Pacific Ocean, so HTTP round-trip times are terrible for most users. If you're on a first-world connection, it shouldn't matter as much.