That's how several major AI advancements have happened. I have seen no evidence that that is the fastest way to make progress right now. I expect that, much like chess engines, it will not take too long before AI is significantly better than AI + human. But right now, my bet is that we are still safely within the window where an AI + human mathematician team is still better than AI alone (at least for the case where the human has learned how to work effectively with the partner....something that this event could possible be good for teaching).

Are they actually autonomous? I’d say subject knowledge at the prompt stage plays a large part towards getting proper results

I think the purpose of an event like this would be to optimize the process so that it isn't just occasionally asking an AI to keep going.