The length of an orthodontic treatment plan is important because it directly affects the outcome of the treatment. If the plan is too short, the teeth may not have enough time to properly shift and settle into their new positions. On the other hand, if the plan is too long, the teeth may start to shift back to their original positions, undoing all the progress that was made.

That's why it's crucial to work with an orthodontist who is experienced and knowledgeable about the length of treatment plans. They need to take into account factors such as the severity of the case, the age of the patient, and any potential complications that may arise.