I've seen this 4pm as well, but (unless anyone knows different) I think it's a myth.
To me,'by' July 1st is not the same as 'before' - so I read that as 'so long as it's in on July 1st, not the 2nd, you're in'. But why take the chance? If you haven't cracked it by midnight tonight, after the door being open for 6 weeks, what could you add?!
I'd hate to work on it late tonight, and then try and send it by e-mail at (say) 1am tomorrow to get an automated reply of 'Sorry, we've stopped accepting them now'. That would be far worse than entering and not getting anywhere - like having the winning lottery numbers but getting to the shop 2 minutes after the console's shut down!
You are not alone! I will shortly be submitting my first play and then will start from scratch on my second this evening! Apart from all the typong errrors it should be OK.
I can feel the spirit of Earnie Wise in the room with me now!
'All we see and seem is but a dream within a dream' Poe