Monza is a classic circuit, but it is an anachronistic and unique one thanks to its high-speed layout.
Its long straights and curves demand low downforce and powerful engines. While Spa is also a low downforce track, at Monza straightline speed is king. This means teams continue to develop Monza-specific packages with tiny rear wings and simplified aero set-ups.
Teams will reduce downforce as much as possible in order to shed the drag associated with it. To do this the teams will start with the shallowest rear wing that they can afford to run.