I would never use "one-too-three." I only invented that phrase to illustrate how a spell-checker works. Evidently the spell-checker assumes that any 2 or more words can be connected with a hyphen. It's a limitation, but it's an entirely predictable limitation, so as long as you don't rely on it to find that kind of error, you can make good use of a spell-checker.

So, would you say "There are four eyes in Mississippi"?

How about "There are two pees in Mississippi"?

Actually, there is probably a lot of pee in Mississippi.