Sorry I missed this post... I feel that sparser ties have more movement in the water, which can translate to more fish appeal... Whenever I tie flags or teasers they're very minimal, a small clump of bucktail and maybe a strand or two of krystal flash. Same goes with my flies.
Of course this can vary depending on the pattern... But for trout streamers and the standard SW flies (deceivers and clousers) I definitely follow the less-is-more philosophy.
Another benefit is that the less materials you use, the easier it is to build neat, tapered head. There's also less of a chance of materials loosening up.
Of course, it could also just be a confidence thing, just like plugs. Try a couple tied heavy and sparse, and then just retie the ones you catch big on
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