What are the key factors to consider when selecting running shoes for different types of terrain, and how do manufacturers balance the trade-offs between cushioning, support, and traction in their designs? For example, how do trail running shoes differ from road running shoes in terms of midsole material, outsole tread pattern, and upper construction? Are there any specific technologies or features that have been shown to improve performance and reduce the risk of injury on certain types of terrain, such as rocky trails or wet roads? How do running shoes designed for specific terrain types, such as ultra-marathons or obstacle course racing, differ from more general-purpose running shoes? Are there any emerging trends or innovations in running shoe design that are likely to improve performance and comfort on different types of terrain in the future? What are the implications of these trends for runners who frequently switch between different types of terrain, and how can they choose the best shoe for their needs?