At several points in 2012–2013 I held the world record for beggar-my-neighbour game length. Richard P Mann curates the de facto official registry of record-length games.

Here is the longest game I have discovered (7836 turns, 1084 tricks):
player 1: ------AQ--K---------KJ---A
player 2: -K-A--J--K----Q-J----AJ-QQ