I am using Outlook Calendar to view my weekly schedule and I want to setup three possible appointment slots. The appointments may be different lengths but at the same time. So I want to add three columns to my calendar to keep it from getting jumbled around with the auto arrangement Outlook has.
How about creating multiple calendars (basically add them like subfolders of your normal calendar by right clicking > new calendar) then you can tick them to view all at once, overlaid on one another.
It sounds like you are trying to book several resources or other people (since I assume you are not trying to be in three places at once), so this approach avoids annoying 'conflict' messages, and means you can actually isolate each one if you need to.
If items don't conflict, it uses the full width of a column, or resizes to half / thirds as necessary for parallel items, so you get the best of both worlds there.
When you click on an item, the calendar it sits in is automatically brought to the front.
Hope this helps
Could you use categories to tell appointments apart, then not needing to actually divide the day into columns? With categories you can tell the appointments apart by their color, like in this screenshot: