Added entry in which the name is not controlled in an authority file or list. It is also used for names that have not been formulated according to cataloging rules. Names may be of any type (e.g., personal, corporate, meeting).Sounds like the field to use when the names aren't in LCNAF or some other file.
Used when one of the other access fields (e.g., 1XX (Headings) or 7XX (Added Entries)) cannot be used because the level of control and/or structure of the name does not meet the requirements of the other access fields. Field 720 should not be used for uncontrolled names intended to provide subject access. In that case, field 653 (Index Term-Uncontrolled) is preferred.
Just asking, am I missing something?
It has been suggested, in a comment, that perhaps these are controlled in a local database. Maybe, but in a shared cataloging environment where we don't have access to the local database is it good policy? Just asking. I can see if they were in the German or French or Brazilian authority files but something local not so much. I very rarely see the 720, are people using it? Am I just not clear on the concept?