What is the guarantee that it is archival?
What independent laboratory has tested this?
You have said your fixing technique 'where the fixer is near exhaustion'. From my reading of CEK Mees the worst case for fixer is when it is near exhaustion, so I quote Mees 'When exhausted on nearly exhausted, fixing baths are used, thorough washing does not remove all the silver form the emulation, even if the time is increased several times over the time required for clearing. This apparent mordanting of complex of complex silver ions by the gelatin may be overcome by the use of a second fresh fixing bath following the exhausted bath."
I have run my own, hardly scientific, test on weak one-shot fixer on paper. I did three prints all the same exposure. I developed all at the same time. Two (1 & 2) I did my normal process and the third (3) I did develop and fixed in diluted fix. I washed all for 1 hour I then placed 2 and 3 in part B of sepia toner. No part A bleaching. I left them in for 30 min. I compared 1,2,&3. 3 showed shift from 1. 2 should the very slightest tone shift. I returned 2 and 3 to the part B bath, 1 was in water at the same time. I left them in about an hour and 15min. At this time there were clear signs discoloration in the 3 print, is was far from being even or consistent, print 2 did not have any further preceptable change.
I did this three or four weeks ago when I saw your post of guaranteed 'archival' . I did not post my finding as I thought to just leave it alone and tossed the prints but not my notes. But I see this post all too often and too many beginners will think this it a great way to save money and not keep stock fixer around. It is false economy, and false science.
Where is your proof of " guaranteed 'archival' " ?