The bow will be able to change cams. Your particular cams will adjust a specific ammount of length. They will have different cams for that same bow that will also adjust to different specific draw lengths.

Look at Hoyts cam 1/2. They have numbered cams. A #6 cam on a v-tec will adjust from 28.5 - 30 inches if I remember correctly. But they also have a #5 cam which is the same cam design but a tad bit smaller. This one will have a shorter adjustment range. They also have a # 4 cam etc... etc... All the same cam geometry but each made to adjust a specific ammount and outside that ammount you would go to a larger or smaller cam.

Just like anything outside a 30 inch draw, 70 pounds, and 350 grain arrow will give different speeds.