Driving to the End of Contacts

I saw yesterday, that Wyatt really need work on driving to the end of contacts.  He is fine if I am beside or ahead of him but tends to stop early when I am behind him.  This has been a real problem in NADAC Chances when there is a contact with the line behind or at the contact.  I got out some targets but he only did well with the big white ones so back to the drawing board with big, white targets fading out to clear and smaller ones and different colors.