Every year, EAG London tends to be held in May/early June. In the UK, >90% of your degree comes from performance on final exams. These take place from May to June, and the norm is to study for at least a month. This means many talented UK undergraduates might not attend EAG London because they are too busy studying. Since travel is no longer reimbursed for the USA EAGs from the UK, this means that many talented undergraduates at UK schools cannot attend any EAGs.
For example, I currently attend Oxford, and think >30% of the most dedicated undergraduates here do not attend for exam reasons.
I'm pointing this out as I'm hoping this factor is considered when deciding dates in the future.
Ah, I did not realize the US ones are larger, this also makes sense.
I think my final skepticism is that US schools end much earlier than UK schools. I don't think they have finals in late May/early June (except maybe Stanford?). So I'm skeptical that there isn't a way to do this so that all final exams are avoided?