If the time is available, then by all means, let him learn. The problem is that the painter is working in a shop and I know if I was managing the shop the decision that I'd have to make would be to get it done, in and out, even if it was slow. The reason being that sometimes learning is trial and error, trial and error cost money in wages (unless the guy is flat rate) and materials...let alone booth time. That's the way management needs to think in order to be successful in our competitive insurance driven market.
A lot of ideas and techniques I use today came from people in the trade that shared how to knowledge with me. Practical hands on experience regarding custom work or painting was done on my own time, my own shop and my own materials. It would be great if there was shop out there that paid painters to gain that experience and there might be the odd one here and there but, for the most part, it's up to the painter to pursue the art side of painting on there own time.
Mike, again, so true about laying out two stripes exactly the same. Especially if there is shading/blending air brush work involved A painter needs to know his materials, equipment and have the experience to make both sides identical.