Only when at 45deg to joists 
Not true, 5/4 can be up 16". 2x decking can be up to 24"
I should clarify. When 5/4 is run diagonal to the joists, the joists must be 12” OC.
I posted my comment thinking about the pic in the original post.
I know it’s an old post. I see a bore in the middle 3rd of joist… LOL
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I have seen a deck, with an octagonal gazebo on one end, where the gazebo joists radiated out to the rim joists like spokes on a wheel.
I have also seen a house, built in a shape similar to a boomerang, where there were floor joists running in three different directions.