Do not re-publish binaries if no changes have been made to the binary since the Page or Component was last published.
Reasoning: With DXA and DD4T, we publish a lot more content today than we originally did when we published only static HTML. In the old days, we would only call AddBinary and publish the binary if it was used int he display of that Page. We would rarely have more than 3 or 4 binaries per Page being published.
However, today with DD4T and DXA, we call AddBinary on every Multimedia Link Component in the existing Component, and every one in the linked-to Component, for all Components within the Link Level. This can result in dozens of Binaries being rendered and published for each Page. 98% of the time, these Binary Components are not new, and do not need to be re-published. They already exist in the Content Delivery system!
Request: Only publish new Binaries or Binaries that have changed since the last publish time of this Page.
Result: Much much faster publish times and more happy customers (and Deployers!)