Evening I'm good with, but we're looking at late night to an early morning ending.
90 seconds per pick x 22 rounds x 12 teams = a possibility of 6.6 hours. I know that in the first couple of rounds it shouldn't be a big issue, but history tells me that nearer the end of the draft most teams will use most of the clock.
A five hour draft is not out of the question. That would have an end time of 1am Central with the current settings.