In education we do it so that nobody freaks out at a blank page while thinking they have missing print error. Page numbers with Page 1 of 2 format is also used for this reason.
The blank pages are usually to do with double sided printing, with starting a new sections on a new page, and detachable sheets not removing exam content such as answer sheets. We also have to create a back page which is blank to that the exam can be issued without exposing it.

