In many situations, I think making something simple is knowing when to make a special case. And I’d further guess that usually you don’t want to make one. Here’s an example where someone did not make a special case.
Eric Sink lives in the same city as University of Illinois. He ordered a Rose Bowl ticket, and here’s what he said happened:
“I laughed out loud. UPS Overnight? I live right here in Champaign-Urbana. The University of Illinois Athletic Ticket Office is less than two miles from my office. Surely I could just go over during my lunch hour and pick them up?
“No, I suppose not. These folks are trying to process orders for over 25,000 tickets and they have very little time to do it. They probably just want to have one standard method of handling them all. Dealing with the special cases would slow everything down.”
He goes on to show another example of when a special case was the better choice.
“Sure enough — my tickets were being sent 1.8 miles by ‘Next Day Air.’ At this point, I fully expected that this envelope would be traveling across town by way of O’Hare.
“Much to my surprise, UPS actually figured out that it was already in its destination city”
I’m not sure it is always so obvious when to make the special case. There is unlikely to be any formula to help you decide. One of the troubles is that a special case involves a trade-off of whether you’re making things easier on you, or easier on your user. The art is deciding when each is the best choice.