New technical systems are created on the basis of existing systems by different extent of taken over and newly developed and/or adapted subsystems and their linkage. Various approaches aim to characterize these different forms of technical adaptation and to make them formally measurable. The calculation of variation shares according to the model of the PGE is based on the determination of variation types with the help of the C&C²-A modelling of subsystems and the associated reference system element as well as the subsystem structure. Both can generally be selected variably. This contribution investigates the influence of these two parameters on the retrospective analysis of variation shares, using a test bench probe and an actuator in a tooling machine as examples. Variation shares are calculated for different levels of detail of the underlying C&C²-A modelling and subsystem structures with different numbers of subsystems. Observed effects regarding the identification of the variation type of a subsystem as well as regarding the calculation of variation shares for the whole system are discussed. A major conclusion of the investigation is that retrospective analyses of variation shares depend strongly on the two investigated parameters and are mostly not unambiguous.