Silver nitrate is a very old technique that pre-dates the use of ninhydrin. In the past it was often used on paper but also on wood (untreated), cardboard, and cow horns. On paper it is nowadays only used when physical developer cannot be used (due to the nature or size of the object). Physical Developer (PD) is in general more sensitive so preferred over silver nitrate.
Silver nitrate can be used after ninhydrin but there is no place for it in a sequence with PD.
Untreated wood and cardboard boxes are items where the use of silver nitrate solution can be useful.
Print developed with silver nitrate on untreated wood
Detail of print developed with silver nitrate on untreated wood
Discoloration of the wood treated with silver nitrate (after 5 months)