Not every student will be recommended for the PPL Practical Test within the minimum hours as specified under CFR 61.109 Aeronautical experience.

Students train training at non 141 enterprises will migrate from one instructor to another. Thus additional hours required to reach the bar. Even with a curriculum, students acquired by you, additional hours may be required due to poor techniques, habits, deficiencies acquired from prior training.

You should recommend a proven curriculum at the place you are instructing, with appropriate records. Transition to another instructor, due to illness, or moving on, can be smoother. However with no structure, you may find it an uphill effort to have all instructors follow the curriculum of choice.