I had one horse that I trained to drive using these courses. The other two just needed a more consistent driver, giving more consistent cues.
Now, I have driven all my horses safely either in competition or just at home. I feel like they trust me now. They know I will give them some warning before asking them for things, and that I will always (try) to be fair.
These courses took me from not knowing how to put a harness on, to driving in the show ring. Absolutely time and money well spent!