In matters of writing, punctuation is not the most exciting subject. Neither is the matter of compound predicates. However, there is a technique of punctuating compound predicates that can serve the fiction writer well.
The literary critic Stanley Fish wrote several decades ago that a sentence means everything that happens to the reader as he progresses through it. This gives the writer another way to dramatize the actions described in his sentences, and it can easily be applied to compound predicates. Here is a sentence that can be written and punctuated two ways:
The man hesitated and then spoke.
The man hesitated, then spoke.
The comma forces a pause, dramatizing the man’s hesitation. But that dramatization is lost if the sentence is written with the “and,” rushing the reader through to the second action. Here is another example:
The rifle held steady, then wavered.
The rifle held steady and then wavered.
The first example dramatizes the action of holding steady and the pause before wavering; the second de-emphasizes the steadiness and rushes the reader through to the action of wavering.
The principle is this: Use the “and” to rush the reader through the sentence to suggest continuous action, but substitute the comma for “and” to make the reader pause, suggesting a time lapse or at least separation of the predicate’s two actions. Here are several examples from my novel Deadly Additive, written both ways here for comparison of effect:
Kristin and Jocelyn exchanged a questioning glance, then stared again at the door.
Kristin and Jocelyn exchanged a questioning glance and then stared again at the door.
She shivered once, then steeled herself to endure a long, cold night.
She shivered once and then steeled herself to endure a long, cold night.
After jogging half a mile he paused to catch his breath, then proceeded at a walk.
After jogging half a mile he paused to catch his breath and then proceeded at a walk.
He took a sip of his drink, then started in alarm.
He took a sip of his drink and then started in alarm.
Deliberately, he touched his forefinger to his lips, then gently pressed it to hers.
Deliberately, he touched his forefinger to his lips and then gently pressed it to hers.
Both forms are acceptable, but the effect is different—a matter for the writer to choose which is more appropriate for each situation. Speed readers will not notice the difference, of course, but then speed readers miss much that the text of a novel contains.