Handling multiple date table

Hi Team,

I was checking on Time intelligence function in "Definitive Guide to Dax" where in i found the below paragraph which im not able to understand can you please help me understand the same?

This was for handling multiple dates in data model

"Using multiple relationships with a single date table increases the number of measures in the data model. Generally, one only defines the measures that are meaningful with certain dates. If you do not want to handle a large number of measures, or if you want complete freedom of using any measure with any date, then you might consider implementing calculation groups"

Regards,

Husna