I don't get what you're saying Les???
If the foreground fencepost is perfectly in focus, as is the far line of hills, and all at f8 (i.e. most lenses highest IQ), are you saying you'd still stop down to f22???
If so, why?
'Proper' landscapers must have a reason for it, but if it's not DoF it has to be shutter speed and if not that - where's the point as you're introducing more chance of diffraction and risking camera shake/subject blur
Of course I accept that 28mm on a FF may well mean f22 is needed to get the DoF required, but if f11, f8 or even f5.6 did the same DoF job using anything 'slower' is pointless - isn't it ???
DD
I'll ask Charlie, he usually pops in the Red Lion on a Thursday afternoon after he's collected his Giro
Seriously, it's the suggestion of an 'aperture straightjacket' implicit in the thread, a similar argument (and more important IMO) is the fall off in quality you can get at the other end of the aperture scale, for example on my 24-105 F4L, it vignettes slightly at f4 at 24mm, and ever so slightly at f5.6, so following this argument, I have a £500 lens which I should only be shooting at a couple of workable apertures, which is nonsense, I may as well get a point and shoot with these kind of restrictions.
Out in the field, most photographers don't carry a theodolite, or a DOF calculator, some lenses don't have distance scales, and estimating distance is not quite an exact science, therefore to cover bases, in a lot of situations landscape photographers will shoot at f16/22 to make sure they have the scene in focus.
After light, one of the most creative tools photographers have at their fingertips is depth of field, you just need look at the work of recognised portrait/fashion/wildlife/landscape photographers to realise just how important this is. By restricting this to a couple of stops around F5.6 damages such an important creative element of photography
It's unlikely you would see a thread suggesting portrait photographers shouldn't shoot at f2.8 or F4 because the sweet spot of a lens is say F8, they would laugh at the suggestion.
The only lens I use that I don't need to worry about DOF is my sigma 12-24mm, knowing (on a FF body) that f11 covers most bases, but as I don't tend to use this lens for landscapes much (it's just too wide), all the other lenses, I regularly shoot at F16 or f22.
This is an interesting discussion, and I hope in particular, for folk new to photography, they will explore the creative possibilities across all apertures.