One of the most important things to take into account when dealing with a change in a project is what importance of the change is. Is it something that MUST happen (FDA regulation, critical business reason,etc.) or can it be done as outlined in the scope of another project? Like mentioned in some other threads, scope creep can be a very real problem in projects and cause immense delays should a PM decide to implement every little change that comes their way (increasing the amount of work done out of scope). Therefore, the importance and urgency of a change request must be evaluated in a way that balances those things that MUST happen with the timeline and initial scope of the project.