Most every conversation reguarding Web bandwidth issues will eventually lead the conversation into a discussion about caching. Cool! Web caching. And you know what I know about cool? It rarely works. If it worked, then it would be uncool. Here's an argument presented by Sam Ruby on the RSS advisory board public mailing list.
the fact that the HTTP expires header (which *is* widely implemented) may make this value irrelevant - i.e., if you are behind a caching proxy, you can attempt to fetch as often as you like, but you will simply get back the same data
http://groups.yahoo.com/group/rss-public/message/875
Sam is not the only person making this argument. It's a very popular argument on technical mailing list. What is wrong with this argument? It's the words MAY and IF. How many of you put a caching proxy between your Web server and the Internet? How many of you put caching proxy between your home computer and the Internet? Please lift up your hand. Anybody? Hello? Is this on? Web caching is cool!
Your definition of common is different than my own.
Randy
I work in a large organization with Internet access for their employees. No caching proxy. I've worked with many large organization in the past with Internet access for their employees. Only once, did we have a caching proxy. And only because I set it up.
Rare. Not common.
Randy