I'll perform line edits on manuscript of any size or variety, be it an epic fantasy with six hundred pages or a novella with only sixty. Proper punctuation, appropriate word choice, and attention to syntax are my three focal points, but I also home in on tense shifts, instances of passive voice, and things of that nature.
Developmental edits - re: character development, pacing, thematic resonance - come at the end, when I've had some time to mull the manuscript over.