I generally ride alone, and I can't imagine riding without a lock. I usually use a lock when stopping for lunch, and I want it in case of mechanical failure that I can't fix. The plan would be to lock the bike, get myself home, and drive back to pick up my bike. I no longer trust a cable lock. It's not that my bike has such great market value; rather, it could cost a lot to replace it with a new bike of equivalent riding quality.
Where would you be locking your bike? Middle of a big city, maybe not. In a suburb or small city, I think I'd trust my bike to that lock for a trip to buy food. Not overnight, but for 30-45 minutes in broad daylight, I'd probably take the risk.