An example: usually the transistors of a simple current mirror should be matched by one of these techniques, but if you need further slave mirror transistors far apart from the master mirror transistor, i think it's better to place this slave mirror transistor near the circuit which it has to supply, and just route the gate bias to it, instead of geometrically good matching, and routing the current.
For simple current mirrors, matching isn't particularly important, because their currents in most cases don't match very well anyway, because of their - in most cases - different Vds voltages. (If exact matching is needed in such a case, a control loop is necessary.)
And there will be devices that don't have to match to another device, but this is trivial, of course.