Strunk and White in The Elements of Style on varying sentence structure appropriately:
If the writer finds that he has written a series of [loose sentences], he should recast enough of them to remove the monotony, replacing them by simple sentences, by sentences of two clauses joined by a semicolon, by periodic sentences of two clauses, by sentences, loose or periodic, of three clauses – whichever best represent the real relations of the thought.
The real relations of thought. Whatever the real relations of thought are, that’s what should be written. And neither tendency toward baroque structure nor desire for flat, non-hierarchical structure is more important. If sloppiness is the problem, then no number of across-the-board dictates about sentence structure will do anything useful. Instead, the aim must be to represent the real relations of thought that represents the real relations of truth.
What is appropriate will change according to what the content is. After all, if the target were set at the same point all the time, all sentences would look the same: we then might as well rid ourselves of all the rest. We could just lose the power of recursion in language (“We could just lose a certain power. That power is of recursion in language.” Only the Amazonian Pirahã people are claimed to speak like that.). But one context requires one thing, and another context another.
(Those who read classical Chinese may read the 山木 (Shanmu) chapter of Zhuangzi for a more philosophical but memorable articulation of what I mean.)