This is very important for us as well. At the moment, our standard request processing time is 1 week. Majority of our requests get converted into projects. Since the system doesn't automatically change the planned completion date of the request to match the planned completion date of the related project, the system keeps sending overdue emails to the request reviewers. In order to avoid this, we have to either remove the request reviewers from the request after the request gets converted into a project or change the request planned completion date to match the planned completion date of the project. Both of these options are less than ideal and easy to forget this step.
Why would you not want to fix this ---when the completion date of the project should map back onto the request. NOTE: my users get the Late Notifications generated out of Set Up and Requests that are converted to Projects with their OLD planned completion dates are getting pulled in.