Normally 5-7 hours. If I'm doing a decoction mash, easily 7 hours. I'm splitting a mash between boils tomorrow, so to reduce the time spent tomorrow, I'm mashing tonight (bringing to a boil to make sure no more conversion occurs over night)
Did a 1 gallon brew last weekend for the first time...3 hours MAX. I was cooking dinner at the same time during half of it. Very easy and relaxing to change it up from the 5 gallon that I have always done.