The emulsion element of any ( monochrome ) coating is 'archivally' incredibly stable, the issue of archival permanence usually relates to the stability of the substrate base, or any 'subbing' applied to that base to allow the coating of the emulsion layer(s). BUT fundamentally, the 'real' archival issue element actually relates to the chemical take up of the base whilst processing, so, Baryta base is the most stable base but takes up the highest volume of chemistry, so needs the extended wash times to make it archivally permanent. The base used on ART 300 is an incredibly stable base and is archivally excellent but is less porous than Baryta and therefore takes up less chemical into its structure, hence the shorter wash times.
If you balance this to RC products the modern ILFORD RC coatings on RC are very stable and archival, but the base actually has an expected 50 to 80 year life before it could (or will) break down gradually, hence RC product cannot be deemed as 'archivally permanent in the truest sense of the word.
Simon ILFORD photo / HARMAN technology Limited :