You would think it would. My DD uses the neck slot and at times she still gets disconnected from the rear shoulder, and the forearm and bicep separates. This causes a myriad of issues. When she focuses on keeping the bicep and forearm "pinched or tight" then is solves a lot of "connection" issues. I think its also related to her age, and body awareness. You find at least with my DD, that when the separation occures it also coincides with not maintaining posture (Chest and head over the plate), the head comes up and chest often comes up.
Check to make sure she's pulling back into her scap. IMO, tension is the scap will tend to result in the hands staying close to the shoulder during the early part of the swing. Whereas, focus on bicep pinch does not necessarily result in scap tension. Scap tension is an important part of connection.
You are absolutely correct that body awareness is a big part of this.