The standard number of progress monitoring passages from NCRTI and NCII is 20 and that is how many passages we have. After 20 weeks the students should start over at the beginning. Research has shown that the practice effect is not applicable in any meaningful way when passages have been repeated over such a long period of time.
When the progress monitoring plan reaches Form 20, it will start over at the beginning and release Form 1 again. However, this form will be labeled as Form 21 to signify that the plan has released a total of 21 probes. This does not mean that there is a separate form titled Form 21, but simply that the plan is on its 21st probe. Clicking on the form to start the probe will show that Form 21=Form 1, Form 22=Form 2, and so on.