_ALL_ is stated to override all other rules. However, if you use the CART functionality, that is all this preference is good for. You are not allowed special cases. It would be nice if there were specific rules, that it would override _ALL_. This is how we are used to most circ rules working, and this would be more consistent with behavior.
+1 We use the CART functionality but we also have some special collections such as Library of Things and STEM kits that we would like to handle differently.
This sill seems to be the case, as there is a note in bold on the pref: The special term _ALL_ is used on the left side of the colon (:) to affect all items, and overrides all other rules.