I have heard of some submitting before midnight on the west coast or central areas and that was past midnight on the east coast, and they were denied and/or the shop disappeared. I have also seen some grace shown, where in my own case, a shop did not fall off after east coast midnight and I had submitted it technically late by east coast time standards.
And lastly, when I have had a shop that had a range of due dates and I selected the furthest away date, I could still do the shop on the earliest date. (Some shops allow this). So, when midnight occurred on the east coast, I was not affected because my shop had a future due date and they did not count that against me on the typical submission rule for same day. It saved me when I had many shops to enter when I got back home and was entering past midnight. I hope I did not just jinx myself.