When a beginner is introduced to RPM, there is a sensory confusion. There may be a sensory and performance stress. The teacher tries to keep the student engaged in listening - responding mode. The spelling skills can be taught using large lettered stencils which has fewer letters in each.
As the student feels comfortable the stress is reduced, the teacher slowly introduces the full 26 lettered stencils. Pushing the stencils when there is no emotional, sensory or motor readiness may result in slowing down the student's progress.
An RPM teacher will know how to judge the 3 readiness.