If I have a conduit with 6 wires (3 separate circuits), and I want them to split at some point, can I send the conduit (A) to a 4-inch square junction box and then send 2 wires to leave the junction box in conduit B, and 4 wires to leave the junction box in conduit C?

All without splicing, just continuous run through the junction box.

Also, is splicing or no-splicing recommended one way or the other?