There is no predicting how long it takes for a mediation to result in an agreement between the parties.  I usually like to set mediation sessions for two or three hour periods.  Some mediators will set them for a longer period of time, even an entire day in some cases.  As long as the parties are willing to pay for it, most mediators don’t have a problem setting a mediation session for eight hours long, with a lunch break.  I am not sure whether that is completely cost-effective.  If the parties haven’t come to an agreement after three hours but want to try to mediate some more, it sometimes makes more sense to schedule another three-hour session several weeks down the road so that the parties have some time to digest everything that they’ve accomplished so far.  Sometimes a case can resolve itself several weeks after the mediation is done; the parties are able to come together on all the rest of the issues on their own.  My goal is to make mediation affordable, and I also want to make sure my services are cost-effective.