If half box speed held good for all or nearly all films when in users' hands as opposed to the strict test under lab conditions for "true box" or is that "foot speed" then wouldn't it be in film makers interests to say that while true speed is say 400 they advise users to try 320/200 as that is the speed at which film X gives proper/full shadow detail.
Sounds like a bit of "Devil's Advocate" on my part but in reality I'd rather have instructions that rendered sufficient shadow detail at a lower speed than a "faster" film that sacrificed it.
Of course this gums up the works for all the automatic cameras that can only read the DX code and can't be overridden and maybe for the vast majority of users, speed is better than good shadow detail.
I wonder how many here rate their films at 2/3rds to 1/2 of box speed? If enough of we 45,000 APUGers responded under a poll of the say the three top films from each manufacturer this might give newcomers to analogue useful information.
If 44,900 rate say TMax at 400 but only 1000 rate D400 at 400 or vice versa for balance then that might say a lot about the respective film speeds