I noticed an odd thing happen in my Self Service 10.2.1. I logged in on a Mac that had 4 policies waiting for it in a "Required Updates" category that I have for such purposes. Adobe Flash, Firefox, Google Chrome, and MS Office 2016. I clicked on each item in the same order that I listed them here and let them queue up. I watched as they executed... Flash... Chrome... Office... Firefox. The order of execution was not in the order I clicked them. Their respective priorities are the same. They didn't go in alphabetical order. It seems to be random. In this particular case it's not a problem, but sometimes I do have policies that DO need to run last because they force a reboot and I'd hate to have the reboot happen before other updates are installed. The workaround now is to have users click one... install... click the next... install...