External shudders don’t help when it’s 100+f at night and they are just as hot as the surroundings. This is why they’re common in Europe but not tropical countries.
On the contrary, external shutters that are also blinds or bamboo shutters are very common in tropical climates as they allow air circulation while stopping sunlight.
Of course they help in those climates too. It's better if it's 100F inside than 120F, which is what you'll get if you let the sun in with no shade-making device. You'll find ways to get shade in every hot climate, whether arid or humid and no matter what the night temperatures are.
