The default setting in desktop Outlook is to have multiple calendars show up without overlapping. This must be useful for someone, somewhere.
Fortunately, my next door neighbor at work (along with, I suppose, millions of users world-wide) discovered how to change this. There is an arrow at the top tab of each calendar pointing left. Click the arrow to fold that calendar into the next one over.
(The text above describes what I show in the video below.)