From the best we can tell looking at Ryan's Hand. He has these splits written down
on the left: 13:45, 27:30, 41:15, 55:00, on the right 13:51, 27:42, 41:33, 55:24 (and then a final one on the right 55:51)
The splits on the left correspond to a 1:00:05 half and the ones on the right a 1:00:31 half if our calculator is right