One of the best investments we ever made.
I tried 2 inexpensive methods on a small roof section for the past 2 years. First was the metal mesh. Works great for leaves, but the small stuff can still get through, and can eventually clog downstream at the downspout. Then I tried the same HD plastic gutter guard as notrichenough on a small part of the roof. I recently removed a test section of the HD guards and found a bird nest being built directly over the downspout. I decided to go back to the metal screens primarily for two reasons: I still visually spot check gutters about 2x a year, and because you can’t see below the HD guards, they must be removed, which can be a pain. I also found that we had a tendency to have more ice damning over those sections above the HD guards, but that may have been strictly coincidence with different weather patterns those 2 years.
How the heck were birds getting in there? There are no gaps on mine where birds could get in.
I’ve gotten ice dams on mine on the north side of the house where the roof gets little sun. Not sure if the gutter guards contribute to it or not. When they do ice up, the gutter doesn’t fill up with ice, so maybe that’s the difference - the ice builds up quicker with the guards. I’ve got 6’ of ice and water shield on the edge of the roof, so water intrusion hasn’t been an issue, knock on wood.