Regarding the actual exposure range of the "straight" line, I'll have to agree I've never seen 14 stops in any film I've ever tried with any normal CI process. Acros would probably come closest. That's without flare. Under real shooting conditions the straight line would tend to be shorter due to compression at the low end.

Having said all that, I think PeterB may be a little too focused on the straight line. Depending on the film and process, there is usually a range of still very satisfactory local contrast beyond the straight line proper. For example on the upper end in my experience there are usually at least 2 stops at the begining of the shoulder which, for all intents and purposes, have "full" separations.

We're ultimately concerned with print quality (I hope), so we need to keep the film curve in perspective. If you didn't have curves in front of you, you probably wouldn't notice the difference between the straight line and early shoulder while you were printing your highlights. In addition, there is never any guarantee the full range of your shot ends up where you expect it to on the curve anyway. There are too many variables in the field (metering, exposure decision, flare, etc.).