If i remember correctly, Regina is the one character that had the most centric episodes and was in the most flashbacks.
The whole baby story with her, Zelena and Robin should have had more focus...but the balancing simply doesnt work with a half season approach.
This season half is a perfect example of a storyline that should have been a whole season long, 11 episodes for such a story is too little.
We havent seen much of Rumple and Belle, Robin and Regina, Merida, Henry etc.
Personally i love that the focus in this half is on Emma...and Hook, they are my favorite characters...but we have no scenes with Dark Emma and her Parents, Snow and charming scenes in general are very rare at this point.
There was so much more potential in this already awesome storyline, if they would have done it for a full season.
Most of the time i like this approach with having a half season story, it doesnt feel dragged out(the frozen story for example worked perfectly).