The majority of my games at last weekends National Open in Vegas, depended on a temporary pawn sac, or taking advantage of weak squares.
I remember my days of playing in the C section at tournaments. Invariably all the games hinged on one and two move tactics.
1300s drop way more than 1800s
1800s drop way more than 2100s
Only till you get to 2200 and above, that most of the dropping stops, and many factors such as calculation, positional play, etc come into play.
That's from my experience so far though.