While I can't find any specific sources in the field of education, I was taught in engineering school that engineers reviewing the work of another engineer, unless their job specifically required them to review work, was against the code of ethics in Ontario. It looks like this is true as well in the USA which has this tidbit in their code of ethics.[1]
"a. An Engineer in private practice will not review the work of another engineer for the same client, except with the knowledge of such engineer, or unless the connection of such engineer with the work has been terminated."