Spending Endurance is overkill under many circumstances. Especially since the first level of Shyness is rather mild:
book says:
At Level 1, you are a bit reclusive, preferring the company of a select few friends. Though not exactly anti-social, you tend to be quiet around those outside of your circle.
Though I'm not entirely sure whether we're on the same page regarding the interpretation, so I tend to overplay it from time to time just to stay safe.
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I'm still thinking about our previous discussion regarding the buyoff. Whether it's worthwhile/fun to try getting rid of the trait at all and all that. Depending on interpretation, maybe there isn't even a point in ever fully overcoming it. Though another random thought is replacing it with either a different trait, or having a low-level Personality Change that results in oscillating between shyness and a different trait (likely an overcompensatory one).