Allow me to throw a positive In here if i may. All your hairs are not on the same cycle so once you finish you face on the first pass at an average of 90 minutes per appointment. Cleanup takes 15 minutes per appointment you can either just do the 15 or combine longer time with other body parts. Once a week at 15 minutes is alot less then twice a week at 90 minutes. Also as your electrolysis is working up your face on the first pass week by week she should be getting the hairs on the regrow area she has already been to. Takes about 5 minutes per appointment on the average to grab regrow. This throws some variables into your math. Especially for people with faster cycle times takes time off the chart. Also age affects # of hairs regrown in other cycles. For some people 16 months has been sufficient with the occasional 15 minute cleanup here and there. No matter what though, budget for the worst and hope for the best. No good electrolysis person can give you an estimate of how long because everyone is different and no one really knows.