Sensory breaks should NOT be viewed as a reward
Sensory breaks should NOT be viewed as a reward - they are a NEED which promotes self regulation, focus, and engagement. 
Opportunities for Sensory breaks should be given to a neuro diverse child several times throughout the day and should offer the necessary intensity and duration of sensory activities that the child NEEDS on a planned, consistent basis.
In fact sensory integration would benefit ALL children within the classroom setting! Why not introduce regular sensory intervals into the school curriculum?