When 6-inch gutters can help
Larger gutters are often worth discussing when a home has large roof planes, steep sections, valleys that concentrate runoff or an existing system that regularly gets overwhelmed in heavy rain.
Capacity is only part of the answer
A bigger gutter cannot fix a poor downspout layout by itself. Outlet size, downspout placement, pitch and discharge location still matter. The system works as a whole.
A clean finished look
Six-inch gutters also have a stronger visual proportion on many homes. The goal is to choose a size that performs well without making the roof edge look awkward or overbuilt.