See, I always keep my toes pointed slightly out. I have weird knees, so this makes sure that they don't lock up while I'm riding, and it helps me use my calf better. They aren't sticking out completely sideways, but I don't point them completely forward, either. Pointing them out a little helps me keep my heel farther down, because when I point them in, I tip forward and lose my lower leg altogether. Again, bad knees, so I don't know if this is the case with everyone.
You see when your toes are not pointing inward towards the horse you tend to put a lot more pressure from your calf and heel on the horses "accelerator" or side.
It depends on training here, too. I also have a thoroughbred who was as hotheaded as they come. The way he was trained, slight pressure on his side was the motor, and squeezing and sitting forward in the seat is the go faster cue.
Of course, there are a million different ways to train, but riding the way I do, Twende and I have always done well in our Equitation classes and my toes isn't pointed completely forward.