How often
Delaware's environmental agency says gutters should be cleared "approximately twice per year, once in the spring and again in the early fall," and cleaned "whenever clogging occurs."
What happens when they clog
The agency says rainwater can "overflow the gutter and pour into undesirable places," such as in front of a basement window or along the foundation. Standing water near the building can lead to water intrusion and foundation damage.
Downspouts and grading
Downspouts should point away from the structure, and the lawn should be graded so water doesn't collect beside the building. The source gives no specific distance. The sump pump guidance we cite in another post says to discharge sump water at least 20 feet from the house, which is a useful reference when you extend a downspout.
Doing it yourself or hiring it out
The agency notes this can be a DIY job or handled by a gutter cleaning company. Gutter work means ladders, and falls are a real risk, so if you aren't comfortable on one, hire it out. We coordinate gutter cleaning through our exterior partners, alongside Gus's Lawn Care for yard cleanups.
Sources
Every figure above comes from one of these. Where they disagree, the post says so rather than averaging them into a single number.