An automatic document feeder with a drive system that can efficiently handle double-side scanning and accommodate more than one timing sequence for sequentially picking individual sheets from a stack using only two motors—a pick motor and a media motor. The automatic document feeder includes a pickup unit with a pick roller, a set of de-skew rollers, a main media path configured to guide a media sheet from the pickup unit to a scanning region and from the scanning region to an output tray, and a switch-back path configured to guide the media sheet back into the main media path. The drive system is operable to provide a high-speed picking mode and a delayed picking mode. In the high-speed picking mode, the pickup unit is driven by the pick motor to pull a subsequent media sheet from a stack of media sheet as soon as a previously pulled media sheet has passed the pick roller. In the delayed picking mode, the de-skew rollers are driven by the pick motor to advance the media sheet toward the scanning region and the subsequent media sheet is pulled from the stack by the pickup unit when the previously pulled media sheet has passed the de-skewed rollers.