I do seem to have made a habit of doing those transitional/bookend stories, but it hasn't been a formal plan. I'm just drawn to the parts of the TOS setting that allow exploring the main characters going through change and growth rather than just ordinary episodic adventures.
Although I do think it's cool that between The Captain's Oath, Forgotten History, Ex Machina, and The Higher Frontier, I've now told the start and end of both of Kirk's first two tours on the Enterprise. (Well, TMP told the start of the second one, but you know what I mean.) Plus The Buried Age fits the pattern too, following Picard from the end of his command of the Stargazer to the start of his command of the Enterprise-D.