As a freelancer, I am usually hired 3 months before the delivery of the product to help them firefighting. In the end, juniore don't deal with the real issues

As a freelancer, I am usually hired 3 months before the delivery of the product to help them firefighting. In the end, juniore don't deal with the real issues in their code. We, senior developpers, do. Note: after a stroke of lucidity, I stopped accepting those kind of missions.