Gutter cleaning is more than just preventing downspout clogging. It is preventative for roof damage as well. When gutters get full of water and the sun comes out, moss and algae get a chance to grow in the cracks between your shingles and the fascia. It will be unnoticeable by someone from ground level, but once this growth starts, it must be prevented. Moss will create holes and continue to damage your roof and possibly cause leaks. Get your gutters cleaned once or twice per year.