Sometimes selection isn't simple. For example, on Saturday night I set up my alumicruiser to take on the weekly club ride I lead very early each Sunday morning. Chose that bike because there are several 3-6% grades on the route, it has a wide gear range, it's efficient, and it was "its turn". That bike has fenders and is rain-rated, but not my first choice in wet conditions because I don't like getting it too messy.

Wake up at 4 am Sunday morning to steady rain (which wasn't in the forecast). Under these circumstances, I'd typically switch to a different bike that handles mucky conditions better and is easy to keep the drivetrain clean, such as the chrome cruiser with its IGH or the fixie. But I remembered the climbing I'd need to do, which those two bikes are definitely not optimal for. So I stuck with the alumicruiser, had a fine ride in the rain, and gave it a thorough cleaning & on-bike chain flush with WD-40 at the end. So it's nice to have overlap in capabilities.