After the Hot Spot (or warm-up), which is usually about 10 minutes in duration, the Guided Mathematics sessions/rotations begin. Guided Mathematics sessions will vary in length but will usually take 15-20 mins (others). There may be 2 or 3 rotations in a Guided Mathematics programme.
Duration will depend on the purpose of the session, the learning needs of the students, students' level of sustained interest and timetable restraints.