Question: Is it possible to override the 20 posts per page limit for blogs?
There is a number of posts on this site discussing this question (e.g. under this question) and the consensus is that it is not possible. Yes, it is!
Using a web debugging proxy like Charles (you can use the trial version) or Fiddler, enable SSL debugging and set the Filter to SaveCollection, so that you can see the form submission in your debugging tool. Then hit the pen icon, change the two values 20 to 30 or so and submit. Done. Magic.