I have seen that failure mode as well. I cannot emphasise enough that it needs to be like pair-programming. Without the more senior person there, the more junio

I have seen that failure mode as well. I cannot emphasise enough that it needs to be like pair-programming. Without the more senior person there, the more junior person will struggle to know how to get started and need to ask so many initially-ill-formed questions that it will be very slow going.