Difficult to explain my logic with individual coaches, it's been so many years since I started doing it the memory has blurred itself there! I'll try to explain how I do things with the coaches:
Let's say I'm getting on 350409, and it's a winner (which it currently is, one day I'll get it!), I'll then obviously have 4 coaches to choose from. So I'd normally choose a motor coach to start with, so my moves book entry would read a bit like this, with underlines in the relevant places:
350409, in 61619, Manchester Airport -> Manchester Piccadilly (1100,arr 1115)
Now I happen to get it on a different occasion too. This time I'll note which coach I've done already, and then choose another one:
350409, in 61620, Penrith -> Carlisle (1451,arr 1507)
And so on until each coach is done, making it into a Super Dud. As you can imagine it will take a long time to make any 390 a Super Dud, let alone the 700s when they begin operations!
I hope that makes some sort of sense. I believe it started when I was getting the same stuff all the time, so it made things a bit different to do the individual coaches as well. I have many times considered stopping doing that, as obviously it makes it a lot easier to do the big transfer when I get a new book, but I've stuck to the individual coach bashing.
Any questions, do feel free to ask!