IIRC, the bromide byproducts would tend to impede development, not increase it.I can only repeat what others have said to me about this, and its possible that its speculative. But what I gather is that during the 30-60 minutes that the tank sits undisturbed, development products (bromide?) drift towards the bottom of the tank and have the effect of increasing developer activity in the zone where they built up. Its got nothing to do with the speed at which the tank gets filled - as you said, a few seconds cannot possibly make any difference.