The fact is, the kinds of speech appropriate to a freshman course in biology are going to be very different from the kinds of speech appropriate to a senior course in theater. The best person to make a decision about what is appropriate in each context is the professor teaching the course. There is no guarantee that that professor will always make the best decision, but there is little likelihood a university-wide policy would generate a better result. That is because no one involved in creating such a policy would have more knowledge about the content of a particular course and how it is best taught than the person who teaches it on a regular basis.