I think that there can be a lot of value of having second set of hands, especially a set of hands that has a teaching credential (or at least working on a credential) in the classroom. Not as a person who makes copies (though there is value in learning how to juggle inside the classroom and outside the classroom responsibilities) but as a knowledgeable co-teacher (if only part of the time) to decrease the student-teacher ratio. They can help with small group instruction, large group instruction (with the other, more experienced teacher taking a small group), and half the class instruction. Whatever is necessary to impact student learning (which in this case also impacts the new teacher’s learning).
While my school doesn’t have a perfect model, we have an associate teacher program — a credentialed teacher, usually new to the profession, who works with three teachers. Essentially, a third of the day is spent with each teacher. We’re exploring ways to support their transition to fully function and effective homeroom teacher including how to support the three teachers in supporting a new teacher and what skills do they (the associate) need to come in with to be successful and what do we need to spend the year helping them develop. In addition, it takes a certain type of person to want a residency/apprentice year — not everyone sees the value/understands how difficult it can be to be truly effective teacher in your first year of teaching. And to not be effective is a disservice to the students we’re teaching.