Star point in schematics
It really depends on your circuitry and how the digital and analog parts interact with one another.

For example in the circuit below you have a purely digital clock on the right and a radio receiver on the left. In order to minimize the amount of digital noise reaching the analog side it is prudent to connect the grounds and rail using the single point star method as close to the supply terminals as you can. That way digital currents only loop around the wires on the digital side, and vica-versa. 







simulate this circuit &ndash; Schematic created using CircuitLab

However, if the digital side interacts heavily with the analog side it is different.







simulate this circuit

In the above circuit, star connected grounds and power is actually detrimental since the return currents for the digital signals must all pass back through the star point to the micro.

For this kind of circuit, integral single ground and power planes with appropriate layout to keep the signal loops as short as possible is much better.

Since almost all circuit boards tend to be a mix a signals, a common ground plane is, or should be, the standard approach. When necessary the occasional island of ground, usually located in a corner so as not to create a hole in the main ground plane, can be isolated for a any very sensitive circuits.