Listening to an episode of Basic Brewing last night, I heard a guest say that most of the conversion in the mash happens in the first half, and that the mash can thus be cut down as short at 45 minutes.
It seems to me that this would work, especially if you're doing a mini-mash for flavor and it's not life-or-death whether you get the exact right efficiency to hit your target gravity.
What's the lower limit here?