According to me there is no requirement of stoppage at Periyanaickenpalayam as this stop falls withing the Coimbatore City itself, Karamadai can be ok, but I think it is also not necessary as of now, because this Niligiri is only the first train which leaves towards Chennai at night, and this train stops at Coimbatore for at least 20 minutes, so to be on time Extra Stops are not necessary. The other way could be adding the more passenger trains, MEMU towards Coimbatore.