What's even more annoying is when people use something like "three times less" to describe "one-third."

Quit it. Quit it NOW.

Here's a quick math lesson to demonstrate why this is completely wrong:

Let's take a value, and call it "x".
Now three times x, would, of course, be 3*x.
So if something is "three times less" than x, then it is x-(3*x) which is -2x.
And (unless x is 0) -2x does not equal x/3.

If you mean "one-third", say "one-third", or at least "two-thirds less" (or fewer, but that's another node).