I believe the application of single strokes vs double strokes (and combinations thereof) can actually be quite accurately summarised into a few simple points:
1. Which hand needs to be where for the next stroke
2. The 'sound' of the strokes (doubles will always sound different to singles).
3. The ease of manipulating dynamic variations.
A very simple and straightforward demonstration would be to play accented triplets, with accents played FF, and then the non-accented notes played PP. Try it these two ways:
R l r L r l R l r L r l
Or
R l l R l l R l l R l l / L r r L r r L r r L r r
You tell me which way flows better, is more relaxed, and sounds better
.
And of course, the application of more complex linear patterns over the entire set. For this next example, the left hand would stay on the snare, and the right hand could move freely and easily around the entire set:
R l l R l R l R l l R l R l l R
Or with a double accented Paradiddle-diddle played with the doubles on the snare, and the accented hits played on toms, you increase the amount of time each hand has to change between each drum for the last pairs of hits. Plus, again you get the dynamic variation that comes with double strokes. Gavin Harrison loves this pattern mixed with double kicks.
R L r r l l R L r r l l
Or, with kick:
B B R L r r l l B B R L r r l l
Err, I hope this helps clarify things? A fantastic book for learning all these compound linear patterns is Sticking Patterns by Gary Chaffee. Might be a little bit pricey but it was Pete Drummond who recommended it to me and I *highly* recommend that everyone gets it at some point!