A stored car still faces most perils
Theft, vandalism, fire, hail and rodents do not require anybody to be driving. Canceling cover entirely leaves the vehicle exposed to everything except collision, which is the one thing that cannot happen while it is parked.
Comprehensive-only is the sensible middle
Many carriers will reduce a policy to comprehensive while a vehicle is in storage, removing the liability and collision premium. The saving is substantial and the car remains protected against what can actually happen to it.
A lapse costs more than the premium saved
Continuous cover is a rating factor, and a gap of several months moves a driver into a worse tier on return. For a household that will need insurance again in a year, the lapse is the expensive option.