Answer:
The reason we often use long snells (Gary and I have used up to 150ft snell – Saginaw Bay, real clear, real high fish), because at times I believe even the small snap weight may spook fish. Especially when the fish are high in clear water you may have to go to a longer snell to stop spooking. Another choice is to use something like a Bass Pro XPS Keel weight. This in-line weight is holographic, so instead of spooking the fish it is actually an attractant.
The other thing to remember especially in rough water, as your boards sweep and pause, the weight (snap weight or keel/in-line sinker) are moving up and down. With a long snell, the spinner basically has a slow undulating motion whereas with a short snell the spinner will follow the weight and have a quick up and down motion. Which is better? Let the walleyes tell you. Some days it’s one, other days they want the other action.