What To Do With Sinking Seats
There are two main grades of foam, firmness and resilience. HR or high resilience foam retains its feel and ability to bounce back much longer than non HR foam. From there, one makes a selection of soft, medium or firm. This is where sample cushions are valuable. You get to choose which is most comfortable. If there is significant improvement to your comfort with the sample cushion, then a much more costly rebuilding of seat springs are avoided.
Due to the higher cost of HR foam, not all furniture manufacturers and/or upholstery shops use HR foam. One needs to rely upon the reputation of the factory or upholstery shop that you will have the quality foam in your cushions.