An imaging system is equipped with two or more exposure heads that are each able to image either a separate media sheet or a portion of a single media sheet loaded on a media carrier. The imaging time for any combination of media sheets is minimized by providing for the adjustment of the spacing between the dual exposure heads whenever the media configuration changes. In imaging a unitary image using two exposure heads to each image a sub-image, any discontinuity between the end of the first sub-image and the start of the next sub-image is reduced by changing the traversing speed of one of the exposure heads by a fractional amount.