How to properly set up nginx + balancing?

Question

Nginx

There is a scheme in which the initial traffic from the Internet is received by 2 nginx + in the keepalived active-active cluster, which, after processing the traffic, send it to different stands. At the stand, traffic is also met by 2 nginx +, which already scatter traffic between the butt nodes, of which there are 6 upstreams of 2 nodes each. What is the point - is it necessary to collect nginx + nodes in an active-active cluster on the stand, or will it be enough to specify them in the upstream on the main balancer? Will there be any pitfalls?