I don't generally worry about crossing the lines -- I'm typically struggling with my concentration long before I get to the point of wandering over lines, so I'd have pulled off before your rule ever came into effect. I had a pretty scary experience several years ago with being tired -- I mistakenly took an overdose of cold medication, and, after a day of trying to stay awake at work, I went home. Halfway there, I pulled off into a golf-course parking lot to take a nap. I have a vague recollection of deciding to continue on home, but I don't remember if I'd taken the nap, or not. I woke up in bed with no memory of the remaining drive home. You're not going to get where you're trying to go, if you're dead.