Front spoilers work at high speeds based on my years of driving and testing ideas on the road course. No data collection devices or yarn, just a well calibrated seat-of-the-pants-o-meter and observing the operating temps, underhood temps after a run. Spoilers also affect high speed stability. Speeds over 100 mph require a spoiler.
I had a street car [E body] that would tap 130 mph every lap and adding the spoiler made a big difference in cooling and stability.

Some spoiler are better than others, some can be set up to break away. The camero spoiler on a charger is easily installed with the large black plastic push ons for easy break away when you hit that curb...