For contest sites I definitely think they should be updated for each contest held or at least annually. If you follow the procedure I outlined above, it takes little time to update airport and airspace data -- certainly less than an hour. It makes John's life a little simpler also to have the input in an STX file. His tools handle things pretty automatically.

I update the local database (radius about 350 miles) in my glider a couple of times a year. There are material differences every time I do it. After frequency changes, the most common, unfortunately, is airport closures. New ones do open up from time-to-time.

Note also that simply updating airport information does not affect names, numbers, or locations of control points.