I don't think 5 years is a good rule of thumb. Did you get a section I clearance when you bought the home? Was it fumigated (tented) at the time? Was there a treatment for subterranean termites (not treatable by fumigation)? Did you replace any floors or shower enclosures when you bought the house?
A termite inspector is looking for 'wood destroying pests and organisms.' That includes termites but it also includes fungus, dry rot, carpenter bees, and a few other bugs that eat wood.
I would inspect every two years or more often if you see activity around the house like: mud tubes or pellets in the crawlspace, discoloration or sponginess to wood trim and eaves, etc. Wet areas like bathrooms, kitchens, and utility rooms are the most prone to having problems. Keep an eye on your flooring around toilets, showers, and tubs.
You will almost always find termites in fences and decks, even if they have been recently installed. If there is no direct connection to the house (deck or fence attached to wall of house) or metal flashing has been installed in those areas, you should be fine.
Termites love our climate and the fact that Santa Clara was almost all orchards and vineyards 100+ years ago doesn't help. Avoid nationally advertised pest control companies and get a recommendation from your agent as to a fair and reasonable termite company. There are only a handful of companies I trust and a larger number that I don't.