I use tags I custom designed for myself.
I use them to follow threads.
Or reference other passages.
Mark redundancies (either story-wise or language-wise).
Follow and fix story conflicts. (The type you don’t want in your finished book, that is.)
…Anything that requires to navigate to a precise location (and fast), really…
Naming a tag a short name that pertains to its nature/reason-to-be (which I didn’t explain in the post I just linked to – that only came after), makes it that you at all time have kind of a layer of outline visible on top of your actual writing. I find it very useful, I rarely am confused as of what I wrote earlier in the novel, or “what is to come, already?”. (You don’t have to tag everything all over the place, for that. But if you have [=Jenny’sHurt] here and there, mixed up with other tags of the sort, the big picture becomes visible at all times. As an overlay, kind of. – It works.)
Plus, if I global search for [=Jenny’sHurt], I get a list of all documents where the tag is to be found, and can quickly follow/work/fix the sub-story of her getting hurt and why and whatever the consequences are…
. . . . . .
On the side I keep a special document where I also stick the tags, and keep notes about the reason for each of them to be.
It is part of my revision process to make sure, as a final step, that this list of problematic whatevers is cleared. (I mean the conflicts and redundancies ; tags I use to mark threads I don’t care.)