What are some key factors to consider when selecting a saddle to ensure optimal comfort and performance, particularly for those who spend extended periods on their bikes, and how do experts weigh the importance of features such as cutouts, padding, and rail material in their recommendations? Are there any proven methods for determining the ideal saddle shape and size for an individual rider, or is it largely a matter of trial and error? How do factors such as riding style, bike fit, and personal anatomy influence the choice of saddle, and what are some common pitfalls to avoid when making a selection?