The single vane type passes approximately 11% of the debris into the gutter systems and rejects the other 85%. The trough type passes from 4-to-11% of the debris into the trough and/or gutter. The louvered systems pass from 1/2-to-3% of the debris into the seamless gutters. Of the hundreds, and in some cases, thousands of pounds of debris assaulting the gutter covers, this means that something has to clog somewhere and maintenance will be required.