same zone doesnt means same state right. Coimbatore and palakkad falls in same ZONE but different states. Bellary and Guntakkal falls in same state but different zones. Both have different form of issues. If coach numbers of panchaganga increased to 20 or 22 naturally many opt for madgoan or vasco extension. With current premises, I dont think KR Karnataka people accept for such extension as it lose its only one train. Nilambur road Thiruvananthapuram Rajya rani can be easily extended to Nagercoil JN (as per ur logic, same zone even same division) but it will lose its meaning if extended. because RR means some point in state to state capital. Panchaganga is created for such caterance. so losing it to Goa is sensitive issue unless connectivity from KR karnataka to Bangalore is improved.