Product training is like fitness training: few people can afford a one-on-one "personal trainer"—and the same is true of your product training.
The Gain: Product trainer visits are costly, so, using the 80/20 rule, mostly "A" stores gain from training.
The Pain: By limiting training of "B" and "C" stores, you're missing the growth opportunities of training your best sales people—retail store staffers!
You can train your "B" and "C" stores without the pain. Turn retail store staff into expert consumer trainers by educating them about your products with easy-to-use training videos.