Unicycles are not particularly expensive, seem to be light and portable, also fun. This gets me wondering if spending a couple of months to learn riding such a thing would boost a mountain biker's coordination, balance, timing, reaction, fall handling, etc. Or would just riding the intended type of trails be more educational?
To clarify, I am sure that doing something is the best way to get good at it. However, I am also aware of the law of diminishing returns. That is, if one's idea is to be good at mtb, maybe after a lot of riding, they should consider other activities, hat are only somewhat beneficial in the same direction.