I'm not doing the SID thing which is supposed to make shinies easier, so my PID frames should be way up there as far as I understand. Though the only shiny I might be interested in getting is Terrakion.
Even without an RNGed ID, if you make a wide search, you should be able to find a few good IV + shiny PID frames where the PID is not terribly far away from the starting PID frame. For example, the PID frame for my Shiny Jolly Terrakion (with perfect IVs, as well) was only about 110 advances away from the starting frame.