In my experience, a lot of “replication” happens as controls for follow-up experiments.
To give an example I’m familiar with, somebody discovers that the life span of nematodes can be extended by calorie restriction, and they publish their discovery.
That original phenomenon is replicated by another lab that wishes to understand the genetic mechanisms of lifespan extension, and tests whether manipulating genes A, B, or C alters the effect of calorie restriction. In each one of their experiments, they’ll typically measure the life span of “wild type” and mutant nematodes, given a normal or calorie restricted diet. Thus, they replicate the fundamental “calorie restriction extends life span” result several times. They find that gene B is required for nematode life span extension, and publish those findings.
Another group studies the role of gene B in the nervous system of the nematode, and wishes to determine whether specific neurons are responsible for life span extension by calorie restriction. They do a series of experiments where they measure the life span of wild type and mutant B animals with normal or calorie restricted diets, while stimulating specific neurons. Along the way they replicate the original “calorie restriction extends life span” finding, as well as the “and it requries gene B” finding, several times over.
Over the next few decades, the general process of replication and extension continues over many hundreds of interlocking papers. Along the way researchers might fail to replicate a specific result, but do further experiments to determine that some previously unaccounted for variable is the source of the replication failure.
There are plenty of dead ends, where a line of research ends where nobody else is interested in continuing from. Some of those dead ends, unfortunately, may be false positives. Somebody else might have attempted to replicate the experiment and failed, but never published because negative results aren’t sexy. Negative results are also a legitimately harder to establish, because the possibility that the replication failed due to experimenter error has to be excluded.
But yeah, the majority of publications are replicated once or twice, if at all. I’m working on a publication that I hope will be absolutely fascinating to three or four other research groups, and moderately interesting to a couple dozen more. Hopefully a few people will be interested enough to replicate and extend my work.