I put the cover on my wall fold-down washing line yesterday and was a little uncertain how it would perform. It was a still Spring day in Melbourne and I was worried that by blocking the direct sunshine, the cover would prevent my washing from drying. All was OK, although a little slower drying time than expected. However, today was a typically confused Melbourne day with warmish wind and threatening clouds and the cover just paid for itself! I could happily leave the washing out knowing that I didn't need to sprint home to rescue it. Amazing!
Side benefit was that I found it more pleasant hanging out the washing when I was in the shade.