The IG Report noted that in some cases the waterboard was used with far greater frequency than initially indicated, see IG Report at 5, 44, 46, 103-04, and also that it was used in a different manner. See id. at 37 ("[T]he waterboard technique ... was different from the technique described in the DoJ opinion and used in the SERE training. The difference was the manner in which the detainee's breathing was obstructed. At the SERE school and in the DoJ opinion, the subject's airflow is disrupted by the firm application of a damp cloth over the air passages; the interrogator applies a small amount of water to the cloth in a controlled manner. By contrast, the Agency Interrogator ... applied large volumes of water to a cloth that covered the detainee's mouth and nose. One of the psychologists/interrogators acknowledged that the Agency's use of the technique is different from that used in SERE training because it is "for real--and is more poignant and convincing.")
So: two two-hour sessions a day, with six applications of the waterboard each = 12 applications in a day. Though to get up to the permitted 12 minutes of waterboarding in a day (with each use of the waterboard limited to 40 seconds), you'd need 18 applications in a day. Assuming you use the larger 18 applications in one 24-hour period, and do 18 applications on five days within a month, you've waterboarded 90 times--still just half of what they did to KSM.