It's kinda like seeing a doctor. A second opinion never hurts
.
Seriously, even if you're video taping yourself for a self-critique, a good instructor might catch small things you might miss. You can either use what he says or dismiss it, but either way, there's more potential for improvement with a
good instructor.
I've noted too that a fast paced class helps a lot with rapid decision making and walking and chewing gum at the same time
.