Something is very wrong and corrupt if a large field of science, an army of scientists spending billions of dollars, is ruled by one easily repeatable study/experiment, and yet nobody cares to repeat it.
Specifically, results are replicated wherever you want to build on something someone has done. For example I'm making specific glass off of a Nature paper for a totally unrelated use.
If the glass doesn't work out will I publish my results? No, too much work to get rejected.
yes, you want to test your Alzheimer treatment, and you measure the amyloid in the patients before the treatment, and you don't find it in some patients... Are you not going to publish that?
That being said, it's not true that we don't replicate results. We don't intend to, and we don't do it for the sake of replication, but as a matter of conducting experiments we do a lot of replicating.
And negative results are just thrown out.
I suppose if you only value this entire end to end process then the experiment is not being repeated at all, but yeah, most things just get discarded when they don't work.