For me it is a measure of how twisty the track is. For example, I only drive Clio and SB on twister tracks and 60s F1 on less twisty tracks. For me personally, straights are only means to gain speed for high-speed turns. My least favorite courses are those which have long straights followed by sharp turn. Maybe I should also add a column for brake life per mile index .
If I get it right, you discovered the formula which tells scientifically that Monaco is a twisty track and Spa is fast with long straights ? Congratulations !
My opinion... I drive most cars on most tracks, a Clio at Monza has it's own unique challenges, just like an F1 at Toban-Short has. Every track/track configuration combined with every car/car configuration, is it's own unique experience and challenge.
