All inside corners and roof valleys will need a deflector to assure no water runoff. You could use screening however, a deflector is going to ensure proper water flow.

Simple answer, no, they are not foolproof. However, no gutter guards at all will cause headaches, lead to erosion, infestation and a lot of money for repairs and damage. It is much better to have gutter guards to collect most of the debris that can clog your gutters.

Yes. If you want to save time, money and headaches over the long run, gutter guards are definitely a worthwhile investment. Roof corrosion, infestation, erosion of your foundation, all of this can come from full gutters and poor water flow. Think about hat cost and that time and you’ll see the worth of gutter guards.