I have commented about doing a bit of outside writing work. Being assessed is necessarily part of that. For one, the client on whose behalf I do the writing has to approve the piece submitted. I have been fortunate thus far to have accurately understood the assigned guidelines for the pieces I have written, so that they have been accepted with minimal need of additional editing and revision. (I write "additional" because I do revise and proofread before submitting, usually several times. I also typically have another person read my work and comment upon it; there are advantages to having married another writing teacher.)
In addition, the agency through which I get my outside work conducts periodic review of its writers. I am undergoing one such now; how I am classified, and therefore what jobs I can take, depends on the result of the evaluation. While I am confident in my abilities as a writer, I cannot say that I am not at all apprehensive about being assessed; there is always the nagging doubt about the quality of work, always the conviction that the writing could have been better somehow. (This is despite the fairly tight turnaround required of most of the outside projects; the assignment is made a day or so before it is due, which does tend to inhibit reflection and distanced consideration.)
Although it seems like it would be a bad thing to continue to have such feelings, that having them is a reason to stop writing, it is not. Rather, it is an internal motivator for constant work to improve; knowing that I could have done better serves as an impetus for me to do better. It gives me something which I can prove to myself; it gives me a reason to improve. And it never fails to do so; there will always be another goal for me to reach, another way I can better myself and my work. It will never be done, so I will always have a new thing to achieve.
So, students, can you.