When dealing with base 10 representations, multiplying by 10 is a simple matter of adding zeroes;
dividing numbers that end with a zero by two is (usually) an afterthought;
doing both operations in that sequence is (usually) equally trivial, the only effortful thing I have to do is adding or subtracting a multiplicand, once or twice or thrice.

It’s not easier than having the result imprinted in my memory, but it cuts away ~ three quarters of the table.

Nope, went through “(6 × 5) + 6”. Slightly slower, but much more flexible since you can do that with any (base 10 representation of a) number that has a reasonable number of digits.

Fucking Aquaman, that’s an important part of the quote

Somewhat in between, more towards the former I guess?

I wouldn’t say it’s nonsense nor that it should be made fun of, I simply disagree on calling it a “choice”. It’s more like a D&D saving throw, and sometimes the DM just makes it mathematically impossible for you to pass it, but I concede that “choice” is less verbose than that.
I agree that you can change your psychological reaction to everything, and that it’s not easy, but it’s not, like, an API call to a well documented open-source library, and you don’t necessarily have full control over what that change is.

The other interpretation is basically your opinion, but actively dismissing the fact that it’s never not always effortless or painless - I’ve heard that here and there, by people I’m not really fond of.

You should elaborate a bit, I can get two possible interpretations of this - one which I agree should be a more popular opinion, and one which I believe is nonsense and should be made fun of.

WHY IS AN APPLE TREE HE, BUT AN APPLE IS SHE?!

Just wait until you learn about eggs, ears or fingers