When working across multiple nodes in a pipeline calling checkout multiple times on the same scm adds the changelog multiple times even though its identical. If they are sequential this is easy to get around but when they are all inside the same parallel ie when running the same closure across multiple nodes it is not. So I think it makes sense if everything is the same don't bother adding another changeset to the build as it is completely redundant. Note that it appears that polling also polls the scm X times as well