The tag scheduling currently has 4 questions, all of which are about schedulers in multitasking operating systems. While this is technically a special case of scheduling algorithms, topics in operating systems and optimization tend to be disjoint. Should we use the same tag for both, or do we want separate tags (and if so, which)?
I think the sum of all tags should define a question; it is not per se necessary that any given tag applies only to questions of the same kind. Three out of four are tagged operating-system which clarifies sufficiently. I imagine that more theoretical questions would be tagged with optimisation instead.
Additionally, I think we can even gain something when tags overlap subfields: people interested in one can see connections to another they previously were not aware of. If we cage tags into subfields, we can not hope to map the bigger picture in CS to tags. As a special case, applications are tied to the underlying theory.