Ways To Create A Future History Series

Poul Anderson's Technic History and Rustum History are very different. Does it make sense to describe them both as future history series? See the Kipling quotation here.

Ways
(i) Write a number of futuristic stories and compile a Time Chart to link them together. (Heinlein)

(ii) Compile a Time Chart, then set some stories within it. (Anderson, Psychotechnic).

(iii) Write two futuristic series, then link them together. (Asimov, Robots and Empire; Anderson, Technic; Niven, Known Space)

(iv) Write a series, then extend it further into the future. (Anderson, Rustum)

Two Kinds of Future History
(i) Many periods with at least one story and sometimes an entire series set in each period, e.g., periods in the Technic History:

interplanetary exploration
the Grand Survey
the Polesotechnic League
the colonization of Avalon
the Time of Troubles
the early Terran Empire
the later Terran Empire
the Long Night
the Allied Planets
human civilizations in several spiral arms

(ii) Fewer stories but with long gaps, presenting information about earlier and intermediate events. See here.