I don't bother doing much to my chain if I can avoid it. Any lube I put on it is never going to be as good as what was applied to it in the factory and it makes it slimy and black to touch.
I tend to avoid cycling in the rain whenever possible - that's the worst thing for chains. I can't understand why more bikes don't have enclosed chains these days.
If I have to cycle in the rain, I ride my second bike, not my best one, so I'm not so bothered about the chain getting crud on it. Then I replace the chain frequently, as they are not that expensive.
Chain drives lose efficiency quite badly if rusty/full of crud etc and wear quickly. But there is a law of rapid diminishing returns and it's not worth obsessing about.
Hot melt wax was used over 100 years ago and if I were obsessed about lubing my chain, that's probably what I would do. It seeps into all the parts and then stays there, blocking out water and crud. Also, it's dry and doesn't leave you covered in black muck every time you brush against the chain. Here's an example on this page:
Everything you need to about chain lubrication for your bike
www.bikeradar.com