Users who are new to scheduling often ask why they used to be able to see all their crews on the month view, and now they can only view one crew at a time.
The answer lies in how much data you have. Once you go over a certain number of visits, there is too much information on the screen. Performance suffers and it's difficult to get a good picture of everything all at once. So it limits you to viewing the monthly schedule 1 crew at a time.