I really don't see the benefits in stepping behind with your leg. The issue with that is the back leg is suppose to drive in the penultimate step (crow hop, second to least step). By sending the leg behind you basically eliminate the drive from that leg. The drive leg is suppose to set your body up in the right position of staying behind the blocking leg as well as gets extra lateral momentum. I have seen athletes do the behind step but I have never seen it be successful in terms of proper javelin technique. A big misconception is javelin throwing is all about having a big arm. The best throwers understand that you use your legs and core primarily to generate the throw. By crossing behind, you basically cut your leg power out of the throw. Wrapping should be used for athletes with exceptional shoulder/thoracic flexibility as well as proper throwing mechanics. As far as coaching with limited time, my belief is coach the sport right or not at all. There are too many injuries that can be avoided if the athletes spent more time on proper training and technique. There needs to be an emphasis on proper technique not strength which is unfortunately a common occurrence in this event in the US and NCAA. Look up sequence photos or slow down videos to show your athletes as well as record them for comparison. It really helps to see the differences in what a 50 meter throw looks to a 70 meter throw to a 90 meter throw.