With constant cuing every 20 seconds, attention can be sustained for one to five minutes. We need data about the length of rest periods in between sensory stimulation periods. We also need data on the number of sessions per day that are needed to prevent troublesome behaviour.
The length of the sessions could be affected by the selection of cues. The question is: Is there a difference between the length of sessions when sessions A) alternate positive and negative cues or B) provide all positive cues? The longer sessions are the best for that person.