How do you determine shorthand notation?
Well no-one (including me!) can decipher my shorthand!
But given the section where you posted your question, I guess you mean shorthand with respect to the electron configuration of atoms. And so I will address shorthand notation in this context.......
Now given that chemical reactions occur on the basis of sharing and transfer of electrons, we need only to represent the valence shell of electrons; the non-valence shells, the inner core electrons, are along for the ride, and the chemical action only occurs for the valence electrons.......
And so, for say iron,
If I have missed the bus, and this was not relevant to your question, I apologize.........