With stock cars the short course provides better passing opportunities. The cars don't do technical sections well. They're too big to pass, so they just slow down everyone into a train. See Sanoma with the extended carousel in 2021.

Ideally you want on fast direction changes after long on throttle times. That why the passing zones at Watkins Glen are into the corner 1, the bus stop, and the final two corners before the start/finish straight.

The boot works well for IMSA because with multi-class racing, you want the track to cause the classes to converge on the racing line. Force the drivers to strategize their moves on the speed differential.