Outside of basic repairs and regulation, some customers require more in-depth services. When an action is scheduled for reconditioning (i.e. hammer replacement, etc.) this is the best time to consider what other measures can be taken to maximize the results. Many actions are poorly-balanced even from the factory, as the complete geometric relationships between the parts and placement of mass is not taken into full consideration. Even high-end instrument manufacturers normally do not take the time to accurately "balance the action" outside of basic downweight and upweight measurements.
Hammer selection is based not only on the size of the piano, but also the size of the hall in which the piano resides. For instance, while a 7-foot semi-concert grand may usually feel best with a medium-weight set of hammers without geometry changes, if the piano is in a large concert hall seating 2,000+ people, a heavier set of hammers may be more appropriate for achieving the energy level needed to reach the back of the hall. In this case, where the heavier set is used, changes to the geometry of the action (reduced action ratio) are normally necessary to accommodate the players' need for ease of control of the increased mass (without increasing inertia). The touch of newer pianos with little wear and tear can usually be improved with careful analysis and adjustment of chromatic balance weight, reduced inertia in the front of the key, and minimizing friction throughout the action.
I welcome you to initiate a conversation with me about your action, whether it is a newer instrument or due for reconditioning.