I often ride without a helmet when im by myself. Not sayin its safe or that i dont need one, jus that i dont care to put one on. One time i fell goin down hill and got really bad scrapes on my palms (doctors had to scrub them to get the gravel out ouch) and a bad knee gash, didnt hit my head.
From then on i always started to wear gloves. I fell again around Christmas and got some bad road rash on my thigh and also put my hands out, but was wearing gloves. Nothing to the head. Hands were fine, not a scratch. Lesson is wear gloves.