I tried a 1v1v1 last Monday and it was fun, but also not fun. We had Cypher Lords vs Untamed Beasts v Iron Golems (I don't want to introduce my Stormcast yet) and the Iron Golems player found themselves on the wrong side of the map next to an empty space and only got into combat in round 3 - which is when the game ended. The other two players battered each other, and the game was decided on a hidden agenda (the Cypher Lords had models off the floor, and no-one else did).
Had another 1v1 last night and something similar - the game was the Comet and so the comet arrives in round 2, and the game ends on game 3 - the Iron Golems had very little time to get to the location (despite having 3 out of 5 locations reasonably well covered). There wasn't much combat, but it was still fun. Game was decided on the fact the IGs had managed to Rush 2 models to the comet location in round 2 (UB was complacent in R2 and only had 1 model on the comet), smash one defender and then block enough UBs to keep control even though we both had 3 models on the objective. Very close.