Re: What role does length play?
Ah contraire mon frairs. It depends on what the rod is. Plastic, glass, bamboo. Take a 5' boo or glass in tight quarters. Kicks @ss on roll casting, bow and arrow casting and so on. Because of the softness of either boo or glass a short rod will be perfect in that scenario. With a plastic rod (graphite) you will be using the upper half more. Also it depends on the weight of the line. On a larger river you'll be hard pressed to find a better choice then the longer rods. Unless you like to relax and enjoy the fishing. Stalk the fish with a shorter rod. It looks nice to see a great caster throw bamboo.
All in all, fish with what you feel comfortable with.
Life is not like a bowl of cherries. It's more like a jar of ghost peppers. What you eat today might burn your ass tomorrow...