I'm sure one of the longtimers on the board will correct me if I am wrong, but my understanding of the RTW rules is that backtracking is not allowed unless you are forced to backtrack to make a connection; therefore a voluntary backtrack would not be permissible. You have to pick a direction , east or west, and stick with it. One tool I find helpful to make sure my routing is correct is to use the Great Circle Mapper which will give you the direction of every leg of your trip and make sure you don't backtrack.. I don't have the link with me but google Great Circle Mapper and you will find it.