The Auto-Save function, which can be set for every 5 minutes, has not been functional since the train-wreck of 2012. Auto-backup (a different function) works each time you close the file you are working on.
I have complained at least a hundred times to tech support and sales about the auto-save not working, to absolutely no avail.
Going forward, train yourself to click the save button every 5 minutes or so.
If the 2016 program does not have this corrected, I will set my Outlook program to send a complaint e-mail every hour until it is corrected.