Works for all of the depths (in meters), the only one, as you say thats a bit 'out' is the 30m, but, when you look at other tables, e.g., Royal Navy, BSAC etc etc, they all were constantly changing every 5yrs or so, over the 60's / 70's as different 'experiments' released new data. Remember, all deco tables, are essentially built from human test and results.