What's the time based service ?
Vehicles are milage or time.
I'd imagine it's 20k or 2 years. Servicing it every 4 is fools folly as the oil will have a heap of water in from condensation from sitting and won't be doing its job and fuel filters can gunge up from sitting ESP with biofuels contents these days
Like wise rubbers - belts and dampers with a service intervals don be fooled into thinking you have only done half the milage in 10 years or what ever the number is that it doesn't need doing
Probably preaching to the converted but it's a pet hate when someone says I've only done 4000,miles in last 2 years so not going to get it serviced.