Van Staal's yearly service program is often a bit tough to interpret (both for owners and those selling them...) so I just talked to Craig about it since the news of the updated price of servicing has just recently hit the public.
Reels DO NOT need to go back every year. The idea of required yearly service is a hangover from the CT days, and hasn't been in effect for quite a while. It is recommended, if you regularly and completely submerge the reel, that you do so. If you're just getting splashed, it is unlikely you would want or need to send it back. If you have several reels (many VS owners do) and one spends all it's time as a back up or sees minimal service it's really pointless to send it back every year. If your main reel is running flawlessly at the end of the season, rinse it off and put it in storage and wait for spring. Sending it back isn't required.
If you do wait 5 years and you fish the reel senseless, there is the possibility that you'll have to pay for parts outside the normal line roller, drag washers, and o-rings. Whether a yearly servicing or waiting 5, 7 or 10 years makes more sense financially for you is your call.
Any additional questions can be posted here (and I'll do my best to answer them) or even better send them directly to the source, Craig Cantelmo at
ccantelmo@vanstaal.com