I think this is a very good question! The case I was thinking of is a highway I was in last week, where temporary work has one of the directions going through

I think this is a very good question! The case I was thinking of is a highway I was in last week, where temporary work has one of the directions going through the other direction, so the 2+emergency lanes in one direction become 2 lanes without emergency in one direction and one lane in the opposite one. In this case, there are temporary lane markings on the ground indicating you should not follow the old ones, but rather align yourself further to the right then you would normally do. OTOH, I am familiar with the situation in Rome where often the lane markings are deleted and a road may be 2-3-4 lanes depending on how people queue up, in which case people would generally rely on social/experience cues, which I'm unable to formalize.