This might seem like a dumb question coming from someone who has never run over 30 miles or so at once, but in order to complete the WS 100 in under 24 hours you have to average about 14 minute miles. Why exactly is that difficult to do? If you jogged a 9-10 minute mile and walked a 20 minute mile, alternating each mile, you would be able to do it. Doesn't strike me as all that challenging. Is it the elevation? That you can't run a 9-10 minute mile on much of the course because of the hills?