There is a lot of mystique surrounding mastering, but it does not do anything that is essentially different to the things you do when mixing. While there are some mechanical things about mastering (such as fixing the beginnings and endings of tracks), the most critical thing about mastering is to be able to listen to something, identify what is needed to refine it, and then to know what tool you need to use to achieve it.
The main elements are:
* dealing with artefacts (i.e. trimming the material and fixing things that shouldn't be there, e.g. a click or a pop)
* dealing with the acoustic balance (i.e. dealing with frequencies that are too dominant, or not dominant enough)
* dealing with the dynamics (i.e. working with compression and limiting to draw consistency between a set of tracks, or to increase the presence of an individual track).
Knowing what settings someone has used on a plug-in for a particular track does not tell you anything about the generality of the process. It tells you what specific thing was done to that track, but not the rationale for it.