As a result, the life of a PDC bit is limited. In other words, a PDC bit can drill only a certain distance or footage. To extend the life of a PDC bit, more diamond volumes or more PDC cutters are used. One method is to use backup cutters that form a second cutting layer in addition to a first cutting layer formed by primary cutters. Figure 1a shows that, in conventional designs, backup cutters were located rotationally behind their primary cutters on the same blades. Field observations confirm that backup cutters in conventional designs remove much less formation compared with their primary cutters but do wear at the same level as their primary cutters. Figure 1b depicts a typical case in which a backup cutter has similar wear as its primary cutter. The backup cutters might not be used properly in conventional designs. Although some successful runs have been reported (e.g., Gonzales et al. 2011; Teasdale et al. 2013; King et al. 2015; Abdullah et al. 2016), bit performance might be improved further if the angular locations and the underexposure of backup cutters are optimized.