The BR system with feather could require eleven without getting in to the complexities of route indicator boxes, but 'The whole chicken' just does not happen in practice, and a model is very unlikely to approach Nuneaton levels of complexity:-
This mast (one feather short of the full chicken, the most complex I know of) would require 14 lamps, it has six high(ish) speed routes and three restricting speed routes.
Suzie Tall