OK my question is if Thor is capable of moving at speeds of light via hammer. Wouldn't he also have to have reactions on par with the speed to stop himself from flying threw the planet. Also someone that has had thousands of years in battle said reactions disappear. I would say that's writers not having full knowledge of character.
I think his hammer flies him. It can clearly direct itself based on the very slightest inclinations and desires by Thor, and I think it knows not crash him. Him having lots of battle experience doesn't mean he has superhuman reflexes. He can still have reflexes that are useful in battle without them being superhuman.
His hammer gives him flight speed, not combat or reactionary speed.