That is precisely why I bet on greyhounds and give the horses and trots a miss. Dogs are VERY VERY consistent. They are creatures of habit - a wide runner will always be a wide runner. A slow beginner will begin slowly 9 times out of ten. A railer will always look for the rails.
Therefore, times are everything in greyhound racing. As I said on another thread, I have been averaging a POT of 15% on the dogs for years now - to do that on the horses would take me probably three times the work and even then, you have the dreaded "bad ride" to contend with.