What is in the lead: The Calender or Project-Options Calendar settings in MS Project Pro?

[Hans_Fransen]

Description
Within MS Project you can set the calendar options (File – Options – Planning – Calendar Options).
This can then be done for specific projects or for all new projects.
I change the settings for working time to: 9 hours and working days to: 31 for all new projects (The store is open on all days of the week)
In my new project this will be taken over. But what is the effect??
The calendar-settings for that new project will not be adjusted!
So what is the effect in my new project if the calendar isn't changed??
I still have a working day of 8 hours and a working month of 20 days in the ProjectCalendar.

Question
What is the effect of the custom settings by changing the Back-stage stage if the standard calendar isn't changed?

[#2]

Hans --

One of the things I learned early on about Microsoft Project is that if you adjust the Calendar settings the Project Options dialog, you absolutely MUST change the schedule on the Project Calendar as well. Otherwise, the calendar and the settings become "out of sync" which can lead to needless confusion. The Hours per day setting is used in the Duration Equation in Microsoft Project. The Days per month setting is used to determine the Duration of a task in days if you manually type the Duration value in Months. In your situation where you entered 31 in the Days per month field, if you type 2 Months in the Duration column for a task, Microsoft Project will calculate a Duration of 62 working days for the task.

The main consequence of not changing the schedule shown on the Project Calendar is confusion as a result of Microsoft Project calculating values that make no sense. Trust me, you need to keep the options settings and the calendar schedule in sync. Hope this helps.

[#3]

Let me add one more thing to Dale's excellent reply. When customizing the Project Calendar, new users often tend to edit the default Standard calendar but that's not a good idea. Rather, if the user needs a custom calendar, it is best practice to create a new calendar, perhaps based on the Standard, with the working days and shift times as needed. The preserves the integrity of the Standard calendar.
John

[#4]

@John Thanks for the addition. I totally agree with you.

[#5]

Hans,
You're welcome and thanks for the feedback. Please consider marking Dale's response as the answer to your question, I only provided a small supplement.
John