Abstract: An apparatus for preparing sets of documents comprises a document conveyor, a shunting station, a folding station, and a controller. A scanner determines the length of the conveyed documents in a set or the space between successive documents sets. The control acts responsive to the determined length or space, and adjusts the cycle speed of the apparatus so that the documents sets are conveyed with a minimum of intervening space without colliding. The invention also includes a method for controlling the apparatus of the invention.