And yet the point is moot because no one is going to use a password like "Av#12GH".

My point was that adding a character to something like "valve tangle hastens accept" is like adding a couple bits to something like "Av#12GH", and yet people feel like it's accomplishing something valuable. They feel that way because "Av#12GH" looks random, but "valve tangle hastens accept" doesn't.

Obviously the literal length of the string is not strictly relevant, and it was probably inarticulate of me to include that.

Knowledge of the pattern has nothing to do with it. That 2048^4 figure is what I mean when I say such a password is strong, and such a figure presumes the attacker knows what system I am using.

Recall that since the passphrase is randomly generated, that 2048^4 is the true probability of guessing it--all the elements of the set are live possibilities. To compete on equal footing, a seven character password must also be randomly generated.

A password is not necessarily strong simply because it spans a large character set. "Sp1d3r!", for example, may as well be a dictionary word. Raw length "spiderspiderspider" is not necessarily helpful either. Randomness is what you need.