It really depends on what spells you are casting, which ones are instant, and what you are trying to accomplish. Some things you can include all in one macro, others become so complex you run out of characters before being half way done with what you are trying to do. If you can get what you want done in one macro, by far that is simpler. On the other hand, juggling a half-dozen Dots on something like an affliction lock is an extreme headache.