When finalizing an extended orchestral project, proof each instrumental section for careless errors. With Sibelius, you can do this very easily with Focus on Staves, and isolate your screen view to a subset of the available instruments. I’m always on the lookout for missing slurs and dynamics, incomplete technique directions (forgetting to end a passage of sul tasto with “norm.” for instance), places to indicate a breath mark in winds and brass, possible problems of bowing in the strings, and many other minutiae that are harder to sort when the eye is searching through a full page.
When all is sorted for each section, return to a full page view and compare dynamic and thematic flow, rhythmic support, and relationships between functional elements. Orchestrators are naturally obsessed with texture – but a bit less with balance, and often very little at first with function (i.e. what is everyone really doing on the page, what are their roles?). We tend to define an orchestral masterpiece as being a seamless aural experience, but in reality it’s the result of tens of thousands of informed decisions, much of them made in second and third draft, or even while editing the publisher’s proofs. Read Beethoven’s letters for an example of this last point, where he will tear his hair out over engraver’s mistakes in letter after letter, then decide to add his own changes, vastly complicating things (but the result is perfection).