At a relatively advanced stage of the interview process, I was asked to complete an additional take-home assignment. I understand the company's reasoning and the importance of such a request, but I would recommend communicating upfront that this might happen. It may also be more effective to request a second assignment right after the first one, especially if the first submission leaves room for improvement. In my case, I completed one assignment, then went through three interviews, and only afterward was asked to do another.
