I don’t know; I’ve cooked beans without pressure cookers for 40 years and with a pressure cooker for 11 years, and if I don’t cook ‘em a while they don’t get done.
Just for kicks and giggles, I’ll try bringing them to pressure and then turning it off and see what happens.
Can I mail them to you for you to sample?
;-)
The point was never that one shouldn’t adjust the cooking time to that particular batch of beans, but that the pressure cooker saves valuable time and fuel.
I know that if I am short of fuel, that I don’t need 40 minutes of cooking, and I sure don’t need 90 to 120 minutes.
Try bringing them to high pressure for 10 minutes or so, and then turn them off and leave alone for an hour or two, and see what the result is.