At AA, the US side on the Bus, we set 300 in the baro field on a Published Visual Approach procedure. FOM 2f.2.8 RNAV Visual and VMS/CVFP Visual Approaches. Approach Procedures 1. d. Enter BARO altitude of 300ft AFE on the PERF APPR page.
I do not know the actual reason for this but we do it at DCA, (Washington National) for the RNAV-F, river visual approach.