Matt, I know you are asking about the deliberate implementation of this.
But taking the question aside, you will probably find that walks to par-3 tees are on average shorter than to par-4’s and 5’s. This because par-3’s are able to traverse the most awkward topography on a site so you have more options for routing.
Back to the question, would it actually reduce wait time when the previous group also has to make the walk? I suspect you are just lengthening the round for all. The trailing group are not leaving the previous green any slower.