Knowing if North Korea is going to do a hydrogen bomb test this year also requires a lot of domain knowledge, and one can invest arbitrary effort into obtaining new data like smuggling oneself into North Korea or interrogating defectors, and may in fact require knowledge it is impossible to obtain outside a particular skull in North Korea. Yet, calibration training still exists and will improve forecasts on both North Korea and on how many M&Ms are in that big jar over there.
Knowing if North Korea is going to do a hydrogen bomb test this year also requires a lot of domain knowledge, and one can invest arbitrary effort into obtaining new data like smuggling oneself into North Korea or interrogating defectors, and may in fact require knowledge it is impossible to obtain outside a particular skull in North Korea. Yet, calibration training still exists and will improve forecasts on both North Korea and on how many M&Ms are in that big jar over there.