Several classes of compounds -- and especially several classes of biochemical compounds -- are traditionally drawn using styles that are specific to those classes. Preferred drawing styles for those classes are discussed within the documentation for each of those classes:
[Do we want to say more here? What if our recommendations conflict with the already-published recommendations?]
Polymers should always be oriented in a strongly horizontal configuration, with bonds between repeating groups oriented toward the far left and far right sides of any monomeric units. This consideration overrides most others. For example, poly(1,4-phenylene) should be drawn with the ring in a horizontal orientation rather than the more usual vertical one.
