Yeah, haven't seen a US based ship at 6 PM for a long time. For me, 5:30 is too early, but 6 would be okay. I did do 8 PM late seating for a while, but that become too late for me. I now just schedule MTD everyday at 6:30 or 7.
ETA: I just did a mock booking for June 19th Explorer and dining times are 5:30 and 8.