Agree with Cobalt.
Another thing is that the mfgs 'cannot' change their recommended procedures because the current ones are 'proven' over decades, which is quite important if it ever came to litigation.
Any change in the official operating conditions would open up a new door for litigation.
Currently, many engines don't make TBO but the owners accept that because ..... many engines don't make TBO and 'everybody else' accepts that as normal.
In recent years, some people have looked into this stuff in more detail.
Lyco are still, right now, doing seminars and presentations in which they pretend that this is all a load of rubbish.