I tried your suggestion without success. To flesh is out, this is what I did.

1. Created a new mmp
2. In that mmp, I create a new Calendar as a copy of "24 Hours" named "Operations" using the Changing Working Time window
3. Made minor customization to "Operations" in the form of an exception day for Christmas
4. Saved the changes by clicking "OK"
5. Entered a few tasks with the default calendar "Standard (Project Calendar)"
6. Entered a few tasks with the default calendar "Standard (Project Calendar)" then changed the default calendar to my "Operations" calendar
7. Entered the duration of the tasks with the "Operations" calendar

This brought the same results. A three day task entered using the "Operation" calendar is represented by a Gantt chart bar of one day despite the Duration column for the task indicating three days. What is likely a simple solution does not appear to fit my definition of "intuitive". All I need is someone to set me on the righteous path of Microsoft Project intuition. I am not comfortable investing more time on this project with this software until I can resolve the seemingly basic problem.