Gutter Leaf Guards and many other gutter contraptions that roofers install on your gutters are to suppose to keep the leaves out. They do keep the debris out, and many times, they keep the rainwater out. In my youtube video called “Gutter Leaf Gaurds” I simulate a small rainstorm. In the video you can see, the water goes right over the gutter leaf gaurd gutter contraption. Even when it rains lightly, some of these systems drip water. I have seen some system cause basement leaks and basement foundation cracks because the overflowing water saturates the soil making it much heaver exerting more pressure against the foundation. Some of these systems can cost as much as $3000. For $3000, you can hire a roofer to clean your gutter and this roofer can inspect your roof once or twice a year for 20 years. Oh did I mention, many of these systems also permit winter ice dams.
This is the link to the Gutter Leaf Gaurd Video https://www.youtube.com/watch?v=_wJUnKaZol4