Preheat oven to 375 degrees. Stir together herbs, garlic, and 3 tablespoons oil; season with salt and pepper. Toss zucchini and squash with 1 tablespoon oil in a separate bowl; season with salt and pepper.
Unfold dough; cover each sheet with a clean, slightly damp kitchen towel. Brush a rimmed baking sheet with butter. Press 1 sheet of dough into baking sheet. Lightly brush dough with butter. Repeat, layering remaining 5 sheets dough and brushing each with butter.
Spread herb mixture over dough. Spread zucchini and squash on top; top with olives. Bake until edges are browned, 25 to 30 minutes. Let cool slightly. Cut into 6 pieces; garnish with oregano. Leftover pieces can be refrigerated, in an airtight container, up to 1 day.