Xavier; I don't use 6x tippet. Fish aren't afraid of monofilament-- they are afraid of unnatural sounds, shadows, movements, and yes, fly drag in some very limited circumstances.

Probably 99% of all non-trout fishing situations don't call for anything smaller than 6 or 8 pound test. I only use 4 tippet sizes: 8#, 10#, 12#, and 15#. I used to use 10 for virtually everything and 15 for very special and rare circumstances. Now I usually either use 8 or 12 because I'm using a different brand of mono.