When I'm brewing 5-10 gallons, I do my mash at whatever temp, sparge if I'm going to, and when there is a couple of gallons in the BK I light the fire and start heating to a boil. My understanding of a mash out is to denature the enzymes therefore not allowing them to continue chewing on the complex sugars while the lauter/sparge is underway. It hardly ever takes more than 20 minutes to complete that part of the process. Is a mash out really necessary? Thanks in advance. 
