Some cookbooks give advice, but it is conflicting. Some say "it should coat the back of a spoon", which I find terribly confusing - my best try to imagine the result will work with a wide range of consistencies. Others don't give instructions at all. I've had recipes say "then add milk to reach cream soup consistency", and I have no idea how much milk to add.
Eating out doesn't make it easier. Our cafeteria offers stuff I would classify as vegetable puree at the soup bar. I'm sure I've had "cream of mushroom soup" somewhere which had the consistency of half-fat dairy cream.
What is the correct, standard consistency some recipes refer to? Is it different for classes of soup (e.g. roux based soup vs. pureed vegetable based soup)? Or is it different for each type of soup, e.g. should a cream of mushroom soup be thinner than pumpkin soup? And how do I recognize that I have achieved the correct consistency?