Final answer:
Revalidation of Effort estimation typically occurs during the Develop phase of the design process, following testing and evaluation as part of refining the design.
Step-by-step explanation:
The phase where Revalidation of Effort estimation occurs in any design process, including engineering design, is often part of the iterative process of developing and refining a design. The last step in the design process, as outlined in the provided reference, is to refine the design. This involves testing and evaluating the design to identify weaknesses and making necessary improvements, which can include revising the effort estimations to ensure they align with the design's limitations and requirements. If the revalidation of time and resource estimations needs to occur, it typically does so after testing and evaluation, and during the refinement of the design, which corresponds to the Develop phase.