The UR plan must provide that—

1. (a) The group performing UR develops written criteria to assess the need for continued stay.

2. (b) The group develops more extensive written criteria for cases that its experience shows are—

   1. (1) Associated with high costs;
   2. (2) Associated with the frequent furnishing of excessive services; or
   3. (3) Attended by physicians whose patterns of care are frequently found to be questionable.