The ceiling on a solo practice is your own hours.
The usual answers are raise rates, hire, or work more. This is the fourth: write the method down well enough that something else can run the parts that are not judgment.
Where a solo practice actually loses time
Rarely in the thinking. It goes to proposals, scheduling, notes, invoices, the follow-ups, the reporting, and the second and third versions of a deliverable. That work is necessary, recurring, and almost entirely writable.
This is the clearest case for the architecture, because there is no team to coordinate. The whole company is one person, so the whole company can be written down by one person.
What you keep
The diagnosis, the recommendation, and the relationship. A consultant is paid for judgment, and delegating judgment would be selling something you no longer make.
What changes is that the judgment stops being surrounded by three hours of assembly. The book's framing is that the system does the two hundred hours and you make the twenty decisions, and for a solo practice that ratio is the entire proposition.
The uncomfortable part
Writing your method down feels like giving it away, and there is a real version of that concern. The book's position is that a method you cannot articulate is also a method you cannot improve, price properly, or hand off when you want a week away from it.