so that a response has time to be effective. People that oppose the wall on the grounds that it "won't work" or "won't stop" those trying to get in don't actually understand how it works. Of course it won't ultimately stop someone provided they have enough time to breach it but the point is to make it so that it takes long enough that they don't have enough time.

That works. I've seen it THOUSANDS of times. Frankly anyone that claims it wouldn't work is an ignorant fool, it works.