What is the main negative effect of changing the due dates of open orders?

Changing the due dates of open orders is a common practice to cope with demand fluctuations, capacity constraints, or material shortages. However, it can have a negative effect on the stability and reliability of the schedule, causing “nervousness”. Nervousness is the tendency of the schedule to change frequently and significantly due to minor changes in inputs or parameters. Nervousness can result in increased costs, reduced efficiency, lower quality, and lower customer satisfaction. To avoid or reduce nervousness, some strategies are: using time fences, freezing the schedule, aggregating the demand, and using safety stock or safety time. References :=

CPIM Exam Content Manual, Module 5: Detailed Schedules, Section 5.1: Capacity Management, p. 18

Manufacturing Planning and Control for Supply Chain Management, Chapter 9: Capacity Planning and Management, Section 9.3: Capacity Planning and Scheduling, pp. 222-223