Yes. I don't want them to lose their flavor (28.2%)
Sometimes, if I remember (46.9%)
No. I never throw mine away. They taste just fine. (25.1%)
Herbs? Spices? Do sprinkles count? (0.0%)
The ones I don't use often I replace when I am cooking something that calls for it and the old one has been on the shelf for a long time.
Some spices do change their flavor, but most, stored properly, are fine.
They did a study with vitamins that show while efficacy decreases slightly (up to 20%), they are fine and won't harm you.
Spices are similar, but herbs are more fragile and delicate, so they don't last as long. Freezing dried herbs give them a longer life, but they will eventually lose all efficacy.