title: Determining RSS refresh rates
body: <p><strong>Do all RSS feeds support <a href="http://pythonhosted.org/feedparser/http-etag.html" rel="nofollow">HTTP ETags</a>/last-modified headers for indicating whether the feed has been updated?</strong></p>
  
  <p>For feeds which do not include last-modified headers, what is the best way of determining how often the feed updates?</p>
  
  <p>I'm hoping to tailor the number of requests I send to each feed based on its update frequency to cut down on bandwidth (following ~2k feeds...)</p>