I almost never use anything but straight high when kicking
Good choice. The reason this is a good choice is because all balls will eventually roll with straight top, natural roll. Naturally rolling balls will rebound off of a rail with a smaller angle (come out longer) than incident, so if you can master and memorize this change for all incident angles then you are golden.
As a general rule, when a ball loses angular momentum with a rail collision (as with a rolling ball) the energy has to go somewhere, and it ends up being transferred into the perpendicular linear momentum (PLM) component to the rail. In other-words, the ball comes off of the rail "faster" orthogonally. The opposite is true, when a sliding ball with no spin hits a rail, energy is transferred from the PLM to angular momentum (spin) and comes off "slower" orthogonally. This is dominant, ignoring energy that is actually lost to the rail rubber itself.
This is also why running English helps keep the incident and rebound angles similar, because it minimizes a change in angular momentum during the collision.