Usually the only thing I am lax on is armored pants, if its a short ride to a job or a friends house I'll wear regular pants. When I lived in Florida on the coast I rode around a few times in shorts with no helmet along the beach at low speeds. It was nice, but I felt naked...
On trips in the summer heat, I find my mesh gear is cooler while riding and sun burns suck when you go the T-shirt and shorts route.
If I know I'll be off the bike a good bit, I'll just wear all leather steel toe work boots instead of my sidi onroad boots. But, thats about the same protection any way.
So, it's most of the gear most of the time. I have crashed once on pavement wearing regular jeans, they don't hold up that well. Broke one helmet, but the Tourmaster jacket and red wing boots held up fine after a 50 mph slide, I slid on my 3/4 jacket and it actually protected my skin. Thankfully I was able to keep my knees up. That crash made me appreciate my Held Steve gloves, those metal things on the palm actually work.