Sirius - what have you siriuously been drinking? Fourteen stops?? Well, certainly not fourteen printable stops unless you like mush or blowouts. A few "straight line" films like old Super XX or Bergger 200 could handle 12 stops; among roll films, Efke R25 would do it. The only thing that realistically does that now is Fomapan 200. Or one might try some exotic developer regimen; but there's typically a penalty in terms of microtonality. What the OP was mentioning was Delta 400. If he's referring to the roll film version of that (vs sheet film), it has a mile-long toe with miserably anemic shadow separation unless it's significant overexposed relative to box speed. But all this refers of course to informed metering which knows exactly how shadows are placed, as well as highlights. Delta 400 might be OK for low-contrast scenes; but it would be one my last choices for anything contrasty. I don't care to go around preaching the Zone System; but in such cases, it's not a bad idea.
I remember well the R3 film (Rollei R3) the recomanded E.I. from Rollei was ISO 6 - ISO 6400 ..

!
It was a couple of years behind (hope I remember correct) what the hell was going on there ?
The same time Ilford indeed gave a "tolerance" of 1 4 stops! I repeat : fourteen !
Guess Sirius Glass haven't drink too much but refered on Ilford's anouncements !
I can't say for sure but I would like to state : Today Ilford can't remember any longer of their announce ment >10 years ago !
What happend in 2003 - 2005 ? Manufacturers of films came under pressure from digital !
So it was just a kind of special marketing anouncements ?
Perhaps - but (just from my point) it is a correct statement ! But we should regard this in a various
context. I remember comercial prints out of the midt 60th till the beginning 70th (also from lab developing of the films).
I never noticed that there was something wrong with that prints.
But I should add : " That kind of comercial prints from consumer labs have a restricted quality !
That is the same case also today - with that exeption that you are willing to pay much more for a special lab print (in high quality)!
(With an experienced darkroom workflow from your own you can of course print bw in better
quality than special comercial labs are able - some of us I should say have a reputation to get
superb bw prints - unreachable from comercial labs)
WITH 14 stops exposure TOLLERANCE

? OF COURSE NOT !
These 14 stops are in regard of a general possibility to get a print in bw what normal amatheuric
photograpers would find OK ! We would waste such prints from Ilford Films 7stops underexposure as trash !
I remember to LOOK on comercial lab developed films out of the end 60th and I can't belive what I noticed : Such lousy negatives I never saw from own workflow out of the midt 70th!
So what was the reason ? Lousy workflow of cheap comercial labs? Bad characteristics of 60th bw film? Total failed exposure ? I guess it was a part of this all

!
But the prints are not soo Bad if you are not looking with that experience view of today !
Conclusion : It is possible to reach prints of normal - borderline characteristics with 14stops tolerance (like Ilford recomanded in the past) because of what ?
Because of more than 14 stops for example 20 stops exposure tollerance would result such a bad
quality that normal housewifes (without any experience in amatheuric photography and without any experience in darkroom) would give it back to the lab that printed / or would waste that prints into scratch !
Indeed there remains allways a group of people we all know who would state : Wow that is looking VERY NICE ! I LOVE YOUR OUTSTANDING PHOTOGRAPHY ! (10 full stops underexposed


)
"EXPOSURE TOLLERANCE" is not a relative term - it is a manufacturers "Trademark"
So we shoud write it in this way " Exposure Tollerance (C) "
with regards
PS : R3 had different layers - if I remember correct the main layer was at ISO 400, a second layer was at around ISO 50 !
But don't beat me therefore (if I am not 100% sure) . The ISO characteristic from a couple of experimental developing (to reach ISO 6400) I definitivly noticed was just ISO 400 !
I guess at ISO 50 the second layer was located.
So 1) ISO 50 was in charge of ISO 50 / ISO25 / ISO 12 / ISO 6 and in other direction on
2) ISO 100 / ISO 200 / ISO 400
I reached superb quality at ISO 400/ISO800 B.T.W.
So the 2. characteristic was ISO 400 : ISO 200/100/50/ AND ISO 800/ ISO 1600 / ISO 3200
AS a result ISO 640O was pure phantasie

. ISO 6 is ALLWAYS POSSIBLE (with low speed bw Films depending on a nice kind of bw developers )