User Configuration > Administrative Templates > Microsoft Project 2016 > Project Options > Calendar
User
HKCU\software\policies\microsoft\office\16.0\ms project\options\calendar
Specifies the number of hours that you want Project to assign to a task when the user enters a duration of one week. If you enable this setting, week-long tasks will be assigned the number of hours that you specified. If you disable or do not configure this setting, the user's default setting is used.