Yes, if I want to print the image, or show it on a site like this, once I get beyond Iso 1200 I just walk away.
In good light, where I'm requiring a high shutter speed and there aren't any serious shadow areas I might try a fraction higher. Or when shooting wildlife just for identification purposes and I'm not displaying the image in public.
I have wasted far too much time attempting to shoot dark scenes by increasing the Iso; then ditching all the results!
ps. When I start to get noise in the shadows around Iso800 I often do two Raw conversions with different noise reduction settings then combine them so the higher noise reduction is only applied to the problem areas.
The same effect can be used by creating a duplicate image layer and merging them together with masking after extra noise reduction has been applied to the layer.
Here is an example of an image which I shot at Iso 800 which, after this noise reduction process, I would regard as being just acceptable.
http://www.pbase.com/crustacean/imag...2/original.jpg