Actually since I use it as a susbtitute of soap, I leave it on each time i want to wash my face till it dries off- then i just rinse it off.
I have tried using it overnight as well and that is helpful too unless your skin is dryer than you can handle.Turns real dry before it starts peeling off. In my view, it has a similar effect to some of the prescription medication that dry up the skin. But this way we don't use any chemicals!!
Mind you, it has to be in conjunction with internal cleanses and healthy diet/living.....because there is no way we can eliminate anything permanently unless we eliminate the root cause.