That is why they call it "school" ... is because you're teaching your dog
Still, your dog will only learn to within whatever limits/excellence his genetic intelligence gives him ...
Some dogs are "born talented" ... while others will remain stupid after 20 schooling sessions ...
Same with human children.
That said, schooling (so long as the dog isn't getting seriously injured) will ALWAYS benefit a dog, if intelligently-planned.
Even the smartest dogs can "learn more" ... and I have seen (what appeared to be) average dogs at first ... get better-and-better after each session.
Jack