If you find that you are scheduling more meetings, and meetings of a shorter length (i.e. 15 minutes), you may want to change the time increments used in your calendar. This will allow you to see all the meetings on your calendar without them overlapping.
You can change the time increments shown in your Outlook calendar to allow for smaller more detailed calendar entries. This will work in Outlook 2003, Outlook 2007, and Outlook 2010.