Thanks! that joins a few dots for me.
i have been swimming all of those as different strokes probably heading to the final destination in a roundabout way.
I totally get the head lead thing, its one of my main focusses getting the head back down in time with the pull and using it to drive the stroke.
And the shoulders remaining straight as kayak
I finished up last night with a stroke that was catching in the front whilt exiting in the back with highelbow catch & highelbow recovery that was just happening through the shoulders / rotation
very fast and automatic as if both arms connected.