Some of the recurring themes in this thread seem to be the question of if it is in a controlled (deliberately choosing not to use the word confined) environment should it be logged? Or if it is just for training should it be logged? Some of the analogies have included things such as the difference between running an Ironman and training for an Ironman.
I would like to put out another analogy. If a licensed private pilot goes to his local airport on a nice sunny day with a light breeze, not to fly to another location, but to practice their pattern work or "touch and goes", then wouldn't it make sense for that pilot to log those hours?
In that context, as I said before, IMHO, any time a diver dives, it makes sense to keep a record of it. Let's not forget, that this is all our logs are, they are a list of what we have done. Whether a dive is spectacular or benign, having a list of what you have done is not a bad thing.