title: One DbContext per web request... why?
body: <p>I have been reading a lot of articles explaining how to set up Entity Framework's <code>DbContext</code> so that only one is created and used per HTTP web request using various DI frameworks.</p>
  
  <p>Why is this a good idea in the first place? What advantages do you gain by using this approach? Are there certain situations where this would be a good idea? Are there things that you can do using this technique that you can't do when instantiating <code>DbContext</code>s per repository method call?</p>