 Well, you know, the organic material, it'll break things down when it makes contact with your shingles. So you don't want organic matter, dirt, leaves, debris, trees, sticks, twigs, whatever it might be. It can damage your roof. Plus it'll clog them up. So you must get that out. If not, that water will sit in there with that debris. It'll harbor mosquitoes and pests that you don't want. It'll give them a breeding ground. It'll rust out your gutter trays if they're not aluminum. You know, there are still gutter trays out there. And if they're not pitched properly, then they won't drain if there's nothing in them.