A project can have multiple resource calendars.
One each for holidays in US, EMEA and APAC regions.
When one does resource allocation thePM tool will automatically calculate the start and end dates based on these various calendars.
It is used in Activity Resource Duration and Cost estimation. PM reviews the resource calendar and sees the availability of skilled resources, the cost of those resources, the geographical location of the resources and takes judicious guess as to which resource he/she is going to assume will perform the activity.
