Yes, this si how it works. You will notice that there are quite a few restaurants that seem to have limited availability, but that is because they are the ones that participate in the CP dinner package.
I always make our ADR's and will make one for the days we plan to attend the CP, however as soon as the package is released I make adjustments, drop one of the Epcot dinners and add CP to our list. I like knowing I have a plan in place 180 days out, but then the changes begin in July....if I have a choice of speakers on our trip the decisions!!!!!!