A Servo can rotate a number of degrees. Most servo's rotate 60 degrees when pushing the stick or wheel of the radio at max, say when it's not 60 degrees cuz I don't know for sure. Servo's in cars like 1/8 scale buggies and truggies work under a lot of load, because of the rough offroading, that's why you can strip/burn weak servo's fast in such cars. In some cars you'll only need for instance 50 degrees of rotating capacity. With End Point Asjustment you can set the max rotation of the servo to a specific percent. If you set the EPA in 50% it will turn 50% less than normal.
You need this (EPA) when the car doesn't need the full amount of turn capacity, cuz when you have too much turning capacity, the servo will work under a lot of load and will go to servo heaven (or hell for that matter).