Although Windows has the ability to change wallpapers at a given interval, the shortest time between intervals is 10 seconds, and for my purposes, that is too long. Any way to change this manually?
The theme files are saved at C:\Users\"your user name"\AppData\Local\Microsoft\Windows\Themes AppData is hidden by default so make sure show hidden folders is enabled in the folder view options.
They can be opened in a text editor and have an interval setting which appears to be in milliseconds. However lowering it below 10000ms did not seem to have any effect. I only spent a few moments fiddling with it though.