I have noticed that when talking about backing on two-handed outfits, many, if not most, posts refer to 30 lb. test backing. Is 30 lb. the norm? If it is, is it the norm because many of you fish for Wset Coast salmon which require heavy tippets, which you would rather have break before your backing? On a 7-weight two-handed outfit to be used for Atlantic Salmon and possibly GL steelhead using 10 lb. tippets is there a good reason not to use 20 lb. Micron?