Could be a good idea. I think it would apply when a discussion is unproductive or repetitive or not fruitful, whereas slow mode is, I think, intended for when discussion is heated and people are responding with adrenaline rather than calm evaluation.
What I might do today in such a case, as a mod, is close the thread with a post redirecting to a new one, where I would try to summarize the position(s) and lay the groundwork for progress. Possibly using quote texts from the previous discussion, And noting that an on-topic discussion is expected of everyone.