@sprig yeah, FAST is optimized so that if you know you are going to render, then apply a specific spatial filter, then a specific temporal filter, it minimizes the POST FILTERING error.
If you optimize noise for a gaussian filter spatially, that gives you blue noise, which is also how you optimize for perceptual error.
But you can optimize for box spatially which is what we usually use!
Check out "D" on this page for something interesting/unsolved about perceptual error. https://github.com/electronicarts/fastnoise/blob/main/FastNoiseDesign.md