I recently brewed a pumpkin ale and used 3 ~3" sticks for a 5 gallon batch along with some cloves and nutmeg. I added the spices about 10 minutes before flame out along with finishing hops. The batch turned out very well, although personally I would tone down the spices a bit for a red ale; perhaps try 1 or 2 sticks? Also, I would definitely recommend using a bag because the spices turned to mush during the boil.