Keep it simple.
- It's hard to build
- It's hard to communicate
- It's hard to diagnose problems
- It's hard to add to
- It's hard to report on
- It's hard to fix it when it breaks (and it will break).
Marketing automation software I've seen isn't particularly setup for managing "sets" of complex workflows. Which leads to the first rule of complex marketing automation workflows.
Workflows do one thing. One thing only.
Complexity like if/then branching is powerful, but the workflow should be designed to do one thing to one group of people.
Doing something else? Enroll them in a separate workflow. Create a framework and naming convention that set of workflows (which is then properly documented). Test this with a sample set (it doesn't have to trigger the marketing actions like sending emails). Test it with a larger sample set. Can your marketing automation system keep up?
MA. Proceed with caution.