After the successful implementation of the mirror feature the next step would be the implementation of a pattern feature which allows the user to do linear or polar or combined patterns of parts.

The idea is:

The user selects a feature, e.g. a hole, or a solid and can define the amount of repetitions by a given distance. This could also be implemented into the sketcher to pattern circles or other geometries even before extruding or rotating them.

Attached are some screenshots made in FreeCAD: