Image formation system capable of starting execution of calibration with timing to start insertion of interleaving paper

An image formation system comprising:

• an image forming apparatus comprising an image forming device that forms an image on a printing sheet to create printed material and a conveyance device that conveys the printing sheet;
• and
• an inserter that inserts an interleaving paper between sheets of the printed material in a manner to supply the interleaving paper downstream of the image forming device in a direction of conveyance of the printing sheet,
• the image forming apparatus further comprising a control device that includes a processor and functions, through the processor executing a control program, as:
• a controller that performs control for allowing the image forming device to execute a print job and allowing the inserter to insert the interleaving paper between the sheets of the printed material at an insertion start timing specified by the print job;
• an executor that executes each individual one of a plurality of calibrations for purpose of retaining and controlling an image quality of the printed material;
• and
• a counter that counts, for each of the plurality of calibrations, a count value of a predetermined item,
• wherein when the plurality of calibrations include a first calibration in which the count value has reached a predetermined target value, the executor determines that a timing to start execution of the first calibration has come and executes the first calibration, and
• wherein when the plurality of calibrations include a second calibration capable of being completed within an interleaving paper insertion time required to insert the interleaving paper or a third calibration capable of being completed within a total time of the interleaving paper insertion time and a predetermined additional time, the executor executes the second calibration or the third calibration in time with the insertion start timing.