On one of my hikes I came across a sign advertising a class in September
by a man who has worked with snakes his whole life: $50 for a
private lesson to snake proof your dog. My question is this: If the
guy actually knows what he is doing, can a dog be snake proofed with a
single lesson? Wouldn't there need to be follow up reinforcement
lessons, say once a year?

Would you guess that an electric collar is used in snake proofing a dog?