Thinking only of shells works for simple reactions, but has anyone ever had a "click" for organic chemistry reactions? Orbitals and shells are the only part of O-Chem that ever made sense to me...it seems like all my friends who "get it" are just practicing their butts off until they arrive at an intuition which isn't amenable to simple rule-based explanations (they seem to know the answers but can't always articulate why).

I'd really like it if organic chemistry made systematic sense.