Do you mean the end tower is not moving 100% of the time or the entire system?  The very outside tower should be moving all the time at 100%.  The rest of the towers will not be running all the time.They only move when the tower to their outside gets far enough ahead they have to catch up.

Your next to the outside tower only has to go about 90% the distance to make a circle the outside one does.  If both towers move at 10 feet per minute the inside one only has to move 9 feet, not 10, to stay in line.  (NOTE: actual numbers depend on the length of the span.  It is probably even less than that.  After being up from 1:00 to 2:00 this morning to shut one down and coming home to a problem with the grandbaby we were keeping, I'm just loo lazy this morning to dig out my paperwork and get actual numbers.)