I've had very drinkable braggot and brochet mead in 3 months with WYeast 1056, granted they were less than 10% ABV. They key is enough healthy yeast, proper fermentation temp, staggered yeast nutrient/energizer, and degassing/vigorous stirring during the first week. In fact my braggot reached terminal gravity in two weeks. Check out this BrewingTV episode