Oh I'm not at all joking. It's better at evaluating quality than producing it blindly. Tell it to grade it's work and it can tell you most of the stuff it did wrong. Tell it to grade it's work again. Keep going through the cycle and you'll get significantly better code.

The thinking should probably include this kind of introspection (give me a million dollars for training and I'll write a paper) but if it doesn't you can just prompt it to.

Think of it as a "you should - and is allowed to - spend more time on this" command, because that is pretty much what it is. The model only gets so much "thinking time" to produce the initial output. By asking it to iterate you're giving it more time to think and iterate.