Final answer:
Corrective motivation allows for adaptability to changing circumstances, which is an improvement over a fixed plan.
Step-by-step explanation:
The theoretical improvement that corrective motivation allows over the concept of a plan is adaptability to changing circumstances. Corrective motivation involves making adjustments and changes based on feedback and results, allowing for flexibility in achieving goals. On the other hand, a plan may have predetermined steps and a fixed schedule that does not account for unexpected changes or new information.