I've seen both sides of FAs helping or not helping. Sometimes they will save space for an empty F seat assuming they will have a bag. Sometimes they will police Y passengers using F space. Sometimes they don't pay attention and it is a free for all. As a poster above said, the bulkheads create a bit of a logjam both in F and Y. You also have all the elites up front who for the most part carry on versus checking. I always get to the gate about 15 minutes before boarding (T-45) to ensure I get a decent bin spot for an eventual quick exit.