Sous vide timing for prime rib
Surveying the top search results for sous vide prime rib, the consensus appears to be about 7 hours, with some leeway on either side.


Cooking Sous vide - 5-10 hours at 137 F.
Big Wayner BBQ - 7 hours at 135 F.
Modernist Cuisine - 5-10 hours at 137 F.
Cave Man Keto - 10 hours at 136.5 F
Sous Vide Recipes - range of temperatures depending on desired donenness, "couple hours"


Note that you don't want to hold prime rib for extended periods (such as overnight) in its bath, as enzymatic action will make it mushy.