But recipes also have to make allowance for variability in things. A recipe might say 1 steak, but that steak may be 1 inch thick or it may be 2.5 inches thick. An inch thick steak will take around an hour.... a 2.5 inch thick steak will take a bit over 3. It makes a difference. People that publish sous vide recipes really should get into the practice of giving an idea of the thickness of things.