212man, I do sympathise with the OP in one regard, in that we have numerous terms to denote one thing that is of importance, temperature. While the terms T5, EGT, ITT might mean something particular to some one with an engineering background, to a pilot it's immaterial, could we change it to "T" for example. Similar with the Ng, Nf, N1 etc.
Sometimes it's just a case of not thinking about things. Just learnt last night that looking at the moon from the N and S hemispheres you see a reverse image. Obvious when you think about it.