Periodic Meeting - Periodicity

Yes.
A periodic meeting that repeats only every 10 months is not really a periodic meeting (in a project management concept)...
Value will be extended to 12 to be able to define a periodic meeting ever year, but I'm not sure it has an interest, because automatically plan a meeting on so long periods will sure propose a meeting date that will not be the real one.
It will surely be more easy to define each meeting one by one, and for instance plan next one during each meeting : then copying the meeting could be a good option.