Yes I do. It's wrong. I know it. I crashed and totalled my previous Vespa because of it. But I got sick and tired of replacing tires, and on the Vespa they went for $100 a pop. And I noticed my street is often strewn with nails and screws. So the habit began.
But after the crash I don't do it on my Vespa anymore. A $100 tire is better than buying a new Vespa or worse.
I still do it on my bike, though. I don't fear nails and screws so much as little things, especially metal, or large objects like rocks and palm fronds.