Workflows need to have ability to design in different parameters to trigger different follow-up emails. Example: Message 1 is sent, those who do not click get message 2, those that click get message 3, those who do not open get message 4. Those that do not click message 2 get message 5. that is a true workflow. Having only 1 trigger for an entire workflow does not work at all, even if the trigger fires for each subsequent email in the workflow.