It would be helpful to be able to mark a field as required before the request/task could be completed, but not until. The "required" aspect would only be triggered when the complete button is clicked. This would allow for fields to be updated over time and required before the request/task can be completed.

A good example: A task used to detail communication with the vendor. The various fields on the task could be updated as the vendor communicates details. Then, before the task can be closed specific fields would need to be updated.