Gondor and Arnor a handfull

well the shire had its own mayor and thain so they could take care of them selves. most other places Elessar probably sent goveners, stewards, or diplomats. Same basic principle Alexander thge great used. The shire, and bree folk could take care of themselves after the scoring of the shire. Bree had some big lok living there so they could defend themselves from orcs and such. there were also rangers around Arnor so they were pretty well taken care of.