Last Saturday a small (~12) group of us did a 50 mile ride at a moderate pace so everyone could stay together. A guy who's been riding with us for 10 years took a three mile pull around mile 40 and as soon as he was done fell off the back and was crawling the rest of the ride. Being the type of ride it was, that forced the rest of us to slow down and nurse him back to the finish. So I agree, some people can ride for years and never learn the basics of group cycling.