Halliday & Matthiessen (2004: 583):
These two resources complement one another in the grammatical realisation of transitions in text. The general principle of complementarity is this: clause complexing does relatively more work locally, while conjunction does relatively more work non-locally and even globally. Clause complexing ‘choreographs’ the local development of text by means of univariate structure, indicating both taxis and type of logico-semantic relation. Conjunction can work together with clause complexing, reinforcing local relations, but it tends to take over from clause complexing as the relations become less local and more global. Looked at from the point of view of lexicogrammar, this means that local organisation tends to be ‘tighter’, whereas the more global organisation tends to be ‘looser’. At the same time, looked at from the point of view of context, the more global organisation is subject to more contextual guidance in the form of generic structure.