Eugene, OR
Twice a year -- spring and fall -- is the common standard for most homes, and it's built directly into ClearView's recurring plans: bi-monthly plans include 2 free gutter cleanings a year, quarterly plans include 1. Homes with a lot of nearby trees, or a moss problem on the roof, often need it more.
Moss debris from the roof washes straight into the gutters and blocks them and the downspouts -- treating the roof for moss cuts down on what keeps landing in the gutters in the first place.
It's a regular standalone service -- you don't need to book anything else with it, though it's also included at no extra charge whenever moss removal or roof washing is done.