Spot fixes don't work well...you need to reshoot the panel for good paint and clearcoat. Unless you are an autopainter, I don't see that as a DIY thing.

I would just wait until it's really, really bad and then do the whole hood. That's what I do with the bumpers.

It use to be that you could spot fix big chips/marks, but these days, with the paint and coats, it's better to just live with it until it is really bad.