Conferences are aware of it too! At least one major conference requires you to either upload your documents at the deadline, or a cryptographic hash of your doc

Conferences are aware of it too! At least one major conference requires you to either upload your documents at the deadline, or a cryptographic hash of your documents, which can be submitted up to a week later. That way, they mitigate the load from the thundering herd of last minute submissions, and thereby avoid the inevitable excuse that the submission server died or that the internet was too clogged to upload their gargantuan video figure by the deadline.