I think 30 is really intended to be the number that says "okay, it's pretty clear something is wrong with this question, and something should probably already have been done to fix it".
I don't believe we need a firm number in mind, but rather ask ourselves, for any given question, "is this an important, common question that will be of use to many people, but which will receive a variety of answers that could be meaningfully combined into a single, comprehensive reference?".
CW questions should be rare. We have a few questions here that are good CW questions, and a few more that probably should be converted to CW.
I'm hesitant to say "no, we don't want more," because there could be good questions that fit the CW criteria out there that just haven't been asked yet. However, I also don't want to say "we do want more," because CW questions don't really fit into the general format of our platform (which is why CW questions and answers don't garner reputation).
I say we continue to judge on a case-by-case basis, and make every effort to identify questions that should be CW, or have CW answers, long before the 30 answer limit is reached.
I also encourage members of the community who think CW might be appropriate to flag the question for moderator attention.