there is no such thing as "systems", especially for players who do not have the technical fundamentals down pat (basically anyone U16 AAA or equivalent)
here's the thing about hockey sense - for me it boils down to being able to count to 3 when you're on the ice. if you're able to get your head up and READ whether you're in a 1vs1, 2vs1, 3vs1; 1vs2 2vs2, 3vs2 or 1vs3, 2vs3 or 3vs3, then you'll only need to be taught how to REACT once or twice to make the right play.
If I ran a practice for young players I dont think I'd use any drills at all, only a few exercises which isolate the 3 basic technical elements, then small area games with different numbers of players on each side, and then give feedback based on how the players interpret & respond to each situation.