What type of bearings do you have in the hubs?

I've always thought of sealed cartridges as disposable. Use them until they're rough, or aren't working for you, then replace.

Lots of variables for loose bearings. Hmmm... that is a good reminder that it is about time to clean and tune my winter bike.

Anyway, for a bike to ride in mostly good weather on pavement, maybe check the cones for adjustment periodically, then clean and re-lube every year or two.