Never seen anyting saying in an actual schematic that all GND wires need to be star connected.
I did see the wires coming to a point as gophert shows, but that is more a block diagram than a useable schematic. In real world you have GND1 plane for everything in input stage, GND2 for signal widgeter plane, and GNDP for output stage, and those three nets meet at one point where they also connect to chassis ground. But that is four wires ultimately, not a whole circuit with 50 wires sneaking to one star point.
You need to consider the relation of schematic to layout. If all the different gnds in gophert´s picture are labeled gnd, than the layouter has no idea unless you sit next to him and make sure he does it how you want it done. If you have the four ground nets and connect those at one point, then you use a "component" called starpoint, which in schematic connects say GND1 to GND2 or other nets, and in layout is a small piece of copper. This makes the ERC and DRC happy and physically connects nets that are separate in schematic in one designated spot.