It depends.
The goal of Herman & Wallace Institute courses is to teach skills that are immediately applicable to a clinical setting. An important part of learning this skill set and preparing for certification is taking time to apply what you learned with patients in a clinical setting.
Some participants, therefore, choose to leave several months between PF1 and their next course. Some, however, choose to condense their coursework over a shorter period of time. Much depends on the participants individual goals, availability and learning style.