The best approach is usually a combination of both.
Automation is useful for predictable parts of the journey. For example, someone who downloads a guide can receive the resource immediately and then a short sequence of useful follow-up emails without the coach having to remember each step manually.
Personal communication becomes more appropriate when the prospect replies, asks a specific question, books a discovery call or reaches a point where an individual conversation would be more useful.
The mistake is treating automation as a replacement for relationships. For a coaching business, it should support the relationship by making sure interested people receive timely, useful communication.
Good automation should make the experience feel more supported, not less human.