User Configuration > Administrative Templates > Microsoft Project 2016 > Project Options > Save > Auto Save Options
User
HKCU\software\policies\microsoft\office\16.0\ms project\options\save
Specifies how often Project should automatically save your projects. This setting is only used by Project if Auto Save has been turned on. If you enable this setting, Project will save users projects at the specified interval. If you disable or do not configure this setting, the user's default setting is used.