Sexton the prob with your 3way/4way hook up is that guy in bathroom "A" turns it off while the guy in bathroom "B" still wants it on. The parallel hook up allows it to stay on if any of the 3 turn it on. The only prob is that if you use switches instead of timers and it's left on you have to go looking for the swithch that turned it on. (I learned that the hard way).
