Simulation of the waiting time at the PAC with a reserved consultation time of (a) 15 min (one working day is shown) and (b) 18 min for patients with ASA class I or II and 30 min for patients with ASA class III or IV (one working day is shown). The aimed service level is a maximum waiting time of 10 min for 95% of all patients (depicted as black horizontal line in the figure). PAC, preoperative assessment clinic.