I think my very late version Schneider 150mm f5.6 Xenar stops down to an unmarked f90, just checked and it's marked to f64, my other Xenar's a 135mm f4.7 and 150mm f4.5 stop to a marked f32.
There's theory and practice/experience and the latter is more important when we're out shooting. As Geoffrey Crawley wrote in 1960/1 there's no point shooting very slow film with a high acutance developer unless you have an excellent lens (or lenses) that can match the resolution of the film/developer combination, and use a good sturdy tripod and optimum aperture.
In the 70's there was a trend to use slow copy films and later Technical Pan in 35mm to achieve so called "LF quality", one problem was they were higher contrast films and the tonality was quite different even in specialist developers, the other was they were very slow.
There were films that could get you close like EFKE 14 (renamed 25) and Agfa AP25 later APX25 but as these were also available a LF sheet film and 120. So we weigh up the advantages/disadvantages, I did shoot AP25/APX25 in 120 in a RF back with my 5x4 camera (it had just been discontinued in 5x4) and that compared extremely well to 5x4 APX100.
The older EFKE 14 was a fantastic sharp fine grained film, 14 was it's Tungsten DIN speed it was more like 16/17 in Daylight, over exposure killed the sharpness and the emulsion was poorly hardened so it was very prone to issues. By the 90's hardening had been improved and the names changed to reflect the Tungsten ASA speed. I've used quite a few boxes in 5x4, and still have half a box left, I've 3 boxes of 10x8 unopened
Ian