PEMF professionals can witness more visible responses when working in areas and refer to them as hot spots. These hot spots are where PEMF professionals will adjust the Magnetic Field Strength (MFS) accordingly, not just during the session, but over the course of multiple sessions. 

When first starting PEMF, MFS remain low and slow. They are built up to the client's tolerance over multiple sessions, and it may differ across sessions and individuals. What may work for one person/animal, may not work for another.