My guess is late war ETO gets overlooked because it is the one planeset that is competitive in the MA. It would be true in the PTO too, except that the tiny Japanese planeset mostly constrains the CT staff to 1944. Just a guess though.
Personally I don't care for rigid schedules, but it does seem to be a fair way to ensure all the settings get equal opportunity. I like what you've done with week 8 as an open, unspecified setup, but maybe it would be better to use it as a "floating" week, which can be inserted into the schedule anywhere - to take advantage of new aircraft from version releases, special anniversary setups, new terrain releases, whatever.
I hate aircraft substitutions, and would rather nix the early war Russian setting than to do it with a bunch of plane subs.
The biggest drawback I see to the plan is for flyers who dislike a particular time period; they could have to wait up to a month for their preferred timeframe to roll around. That might drive some people off. (And I realize you been waiting a LONG time for your late-war ETO, Andi).
Does it have to be chronological? Could the BOB week be followed by late-war PTO, then midwar MTO, then late war ETO, then early war PTO, etc? Maybe an non-linear schedule like that would provide enough variety in time frame while ensuring all setups get their due.
Enough brainstorming from me. Somebody else pipe in here now.