All bicycle chainrings SHOULD be rotated periodically to maximize life and decrease overall wear. This is due to the placement of the power stroke in the rotation..
This is not to be done on geared bicycle due to critically placed shift ramps and pins. Single gear bicycles, though, allow for rotating, so it should be done.
A four hole spider will allow for 90 degrees of rotation for each location. A five hole spider will allow for 72 degrees per location. A White Industries ENO crank will allow 30 degrees per location.
Let's say that you expect a chainring to last 1 year. For traditional spidered cranks, you should rotate the ring 4 to 5 times a year, or every 2.4-3 months, assuming you ride all year.
I scribe the date that the ring was placed in each location to help keep track.
Original position. September 1, 2006
180 degree rotation. December 11, 2006