When you & your opponent are each bowling well but from opposing hands, the advantage is likely to pass from the side that is forced to switch hands because that side will have to judge afresh both the correct grass and weight. You can force your opponent to change hands by delivering a short bowl that crosses the center line and comes to rest in the opponent’s draw. Your opponent will probably get worried about hitting this bowl and promoting it onto the jack and for this reason, may be induced to change hand. This strategy can be seen being practiced in the match between Harlow and Chok
So in this situation shade, your draw shot towards being narrow. If it is short it can block your opponent’s line. If it is perfectly weighted it can possibly trail the jack and if it is behind it becomes a good ‘catcher’ for your subsequent deliveries.
P.S. In the above-linked video Harlow also demonstrates a different tactic. When the draw on both sides is blocked he bowls with more weight for the bare jack and takes it and his bowl into the ditch. This occurs at time 1:16:23 on the video.