The criticism of the 80% rule by Rossh and others (link
)-- ". . .The first stop distance for the Ratio Deco 80% method, when used on dives of 60m/200ft or less, will produce the deepest of all first stop depths. This method does not have any benefit over those at 2 ATA [delta minus the maximum depth] . . .The x% rule was originally designed for use with 270 to 300ft dives at WKPP but needs a correction to remain in context with any other depth. The efforts to extrapolate the rule base from the 300 ft dives to all other depths, have failed to address the change in scale required. "
The gist of this critique is that you're still loading bottom mix inerts at a 80% of max depth deep stop disproportionately for dives less than 60m/200'. (Actually in practice, I'm not doing a "hard" deep stop per se starting at 80% max depth for dives in the 45m/150' to 60m/200' range for 25min BT or less: only a slight 5-10 second pause to arrest the 9m/min [30'/min] ascent from the bottom).
What's the correct interpretation (or reconciliation) between the two deep stop methods?