The only thing that matters in school, as things stand at any rate, is to get as many 16 year olds above a D in as many GCSEs as possible.
So therefore the focus (at least at Secondary level) is on the GCSE syllabus. And the more astute in the profession have been drawing the contents of that down the Key Stages for a while now.
But any professional that cares about their subject, knows that there are holes in many of these syllabi, and perhaps foolhardily attempts to stick their thumbs in the cracks. Because they know, that to do their job well, they should be giving each student the best education they can.