I dry hop with 2 oz. at 72 degrees for 3-5 days. I then remove the hop bag from the secondary and put in a hop bag with 1 oz then put my secondary in the fridge for 3-5 days. After that, I keg it. I don't know if that 1 oz does anything, but my hop aroma and character stay with the beer through the whole keg. Now, if I could get the keg to last a month, maybe I'd know if the flavor diminished over time.