it's hard for me to say what works and what doesn't.
well said. Everyone is different.
for people, 8,000 ft is the official "start line" of altitude illness, although aircraft manufacturers (who pressurize cabins to 8,000 ft equivalent) may be in the process of changing that to 7,000 ft.
And then there are individuals whose sensitivities to altitude vary all over the place; some less than that 7,000, others, say Tibetans, where it may be twice that. Some ( not all) of them are genetically superior, altitude -wise. Then there are species far more altitude-sensitive than humans - some cattle get brisket disease (which is more than simple AMS) when moved to just 3,000-4,000 ft. In a study of cattle moved from Wisconsin to Colorado, brisket disease was the #2 cause of death.
