Helton asked for my thoughts on why it is so hard to score ippon from hiki dou. Wearing my referees hat (or blazer), I would say that of course every case is different, but more often than not it is because few hiki dou have sufficient sae or snap to justify ippon. If that is not the case, then it is because hasuji (angle of the blade), is incorrect.
When you make a hiki men, you do so in a straight line, stepping back to give yourself enough distance to strike with the datotsu bu of the shinai. You also strike in an up/down motion so it is quite simple to generate the momentum to make a strong, sharp cut. With hiki dou you need to ensure that the target is open, lift your hands up to strike, then adjust the hasuji and hit the dou with the correct part of the shinai whilst making one quick step back. In my view it is not easy for many people to do this, hence the poor ratio of successful attacks to attempts.
Dou in any direction is a difficult target. Most shikake or oji dou are unsuccessful because the attacker hits the dou whilst moving across in front of their opponent so that the strike is made with bent arms and is therefore weak. As we have discussed before, a good dou strike should be made directly in front of your opponent, with your right hand pushed forward. If you think about this applied to hiki dou, you have not only to be clear of your opponent from tsubazeriai, but you must give yourself enough room to punch forward with your right hand as you make the attack. So you need to generate significant propulsion from a standing start to do this in one step.
Gyaku dou is even more frequently doomed to failure. Whilst not classed as a hiki technique, the strike is usually made as you step back. With this waza referees are looking for a more powerful cut. The reason behind this is that samurai originally wore daisho (two swords) in their belt and that when the long sword was drawn; the kodachi usually remained in their belt. That meant that a cut to the left dou needed to be strong enough to cut through the hilt before it reached the target.
The only tip I can offer on hiki dou is to start in tsubazeriai by pushing your opponents hands down. He is likely to react by pushing his hands up in a reflex action, exposing the target. You should step back as far as you can starting with your left foot, keeping in a straight line and strike dou as hard as you can by pushing the hands forward, turning your right wrist so that your palm is parallel with the floor. Take another step back after hitting, keeping your shinai tip pointed at your opponents nodo to complete your zanshin.
The last step is to hope that at least two of the three shinpan like dou.