The treatment can be divided into two phases. The first phase is all about bringing the condition under control. You can stick to the following schedule as per the severity of your condition.
If it is mild then 3-5 times/week for a week or two, if it is moderate then 3-5 times/week for between two and three weeks, and if it is severe then 3-5 times/week for between four and five weeks
The second phase is about maintaining the results achieved in the first phase and the schedule is as follows.
If it is mild then once every 2-3 weeks at the highest current setting that is comfortable, if it is moderate then once every week at the highest current setting that is comfortable, and if it is severe then thrice every week at the highest current setting that is comfortable