I think for a 1+4 floor building , 10-12 connections is sufficient.
In 35 flats (2 buildings) 1 building 16 flats thats is 4 flats in one floor.
10-12 are DTH users like TS and Airtel, while rest are Digital Cable.
Now not all may be wanting to change .....So thats why 10-12 i have taken as people who may want to change.