Bro trains run full, you may see end-end available but itll be full at destination, for e.g. in YPR-NZM express people book between YPR-PUNE and it may reach WL, so WL passengers will be allotted the seats which are available between YPR-NZM, PUNE-NZM WL passengers to get allotted in YPR-NZM quota seats, hence trains won't run empty but in some stretch it'll that's it.