Scott, that's certainly true. I agree that a photographer will have to keep different scenarios in mind, but I was thinking, just how tricky is knowing where we stand from a practical standpoint, and how many lenses will any of us have to worry about.
For this exercise, I'm only going to look at FX lenses since this is the D800 forum.
We can eliminate lenses with max apertures of f/2.8 or greater, and I'll also eliminate lenses which aren't at least 200mm since it's unlikely anyone would use a teleconverter on them. That leaves us 12 FX lenses in the Nikon stable.
We can take out 6 of those lenses if we only use a 1.4X teleconverter, as their max aperture is f/4.
So for 6 lenses, and perhaps 12, in the Nikon stable, one would have to worry about the 3 scenarios, but for all practical purposes I think you really have to worry about the f/5.6 and f/8 scenarios and most of the time it will be the f/5.6 scenario.
Without using a teleconverter all the current Nikon lenses will use the f/5.6 scenario at all focal lengths.
If the lens is a prime, the teleconverter magnification will directly dictate the scenario, as will be the case with a fixed max aperture zoom lens, but if you're using a zoom lens with a variable max aperture it could become a complicated mix of scenarios.
Practically speaking, when you're using a teleconverter, with a zoom lens, you're generally using the lens at or close to it's max zoom. Yes I know there are exceptions, but I presume not many. Therefore it will rarely be at any max aperture except it's least open max aperture. So, with an f/5.6 max aperture for the lens itself, you'll jump right to f/8, and its scenario. You'll rarely, if ever, worry about an in between scenario.
Note, I'm discounting above f/8, for practical purposes.
From my personal experience with my AF VR Zoom-Nikkor 80-400mm f/4.5-5.6D ED and the new AF-S version which I tested, with a 1.4X teleconverter taking the lens to f/8, AF is significantly degraded even on a D800 or D4. I found that's true on my AF-S 500mm f/4 with a 2X teleconverter. I find that most of the time with that combination, I'm manually focusing. When the max aperture is just f/8 the amount of light those AF sensors get is mighty small, so they don't work very well at that point, but at f/9.5 or f/11, AF, for all practical purposes comes to a screeching halt.
Therefore I'm going to suggest that in the practical world we need generally only remember 2 scenarios and we'll make out well, and we'll only have to worry about that with a few lenses in our camera bags.