1. A method for controlling an apparatus having an inkjet head for duplex printing, the method comprising: arranging maintenance images among page images prior to printing based on a predetermined condition; causing the apparatus to print a plurality of image patterns in sequence on a first side of a continuous sheet, wherein the plurality of image patterns includes the page images and the maintenance images that have been arranged among the page images prior to printing based on the predetermined condition; causing the apparatus to determine, based on a first side print schedule for printing on the first side of the continuous sheet, a second side print schedule for printing on a second side of the continuous sheet, wherein the second side print schedule is used for printing the plurality of image patterns including the page images and the maintenance images that have been arranged among the page images prior to printing based on the predetermined condition; and causing the apparatus to print a plurality of image patterns in sequence on the second side of the continuous sheet based on the determined second side print schedule after printing the plurality of image patterns on the first side of the continuous sheet, wherein, a second side maintenance image located between one of the page images and a next one of the page images does not overlap with a page image printed on the first side of the continuous sheet, and wherein, a first side maintenance image located between one of the page images and a next one of the page images does not overlap with a page image printed on the second side of the continuous sheet.