Last night I picked up my single Core set and played the Lion vs Crane intro game suggested by the Learn to Play book. My wife and I had a good time and felt no need to buy a second or third core for casual play between us. My slightly elevated play between friends will require a single core per player. (FFG has an excellent single core deck suggestions list: https://images-cdn.fantasyflightgames.com/filer_public/c0/99/c0995a8d-f56b-45e3-801a-054ec7623494/l5r_suggesteddecklists_b.pdf )
I have yet to play this game in a timed environment, but fear that this may not be the best setting for the game. Do I believe, as I play the game, that the average play time will decrease below 2 hours? Absolutely! I'm just not sure this game is truly built to be enjoyed inside of 45 minutes. It feels like chess with cards. Its a game I want to play while drinking a glass of whiskey and conversing with a friend.
The cry for "you must buy 3 cores!" definitely applies to those who want to build 45 card competitive tournament decks now. The casual player will enjoy this game with a single core. But what about "fun"? Is a game forced into a time frame under an hour (or even 50 minutes) fun?