Where should arc fault breaker not be used?
Like GFCI's, AFCI's coverage is being added to Dwelling Units each NEC revision.Under 2017 NEC Article 210.12 (A) "Dwelling Units" almost all 120V 15 and 20 amp branch circuits supplying outlets (see NEC definition for outlets) must be AFCI protected. 

The only circuits not needing protection in a dwelling at this time are Bathrooms, Garages, Crawl Spaces, Attics and Outdoor.

Definition: 
 Outlet: A point on the wiring system at which current is taken to supply utilization equipment. Although receptacles are outlets not all outlets are receptacles. Example light fixture outlet.

Note: AFCI Protection must be installed within 50' of the devices it's protecting.

Hope this helps.