Double pivoting confusion

hi guys, Iwas studying double pivoting technique and I found this link on internet, near the end there’s a section about double pivoting, he uses 2 times the socks4a module with 2 different ports, because packets needs to pass 2 pivot( and before reaching the target network, so packets go first to then to and then to, from what I understood socks4a module starts a proxy on a local ports and use metasploit routing table, so isn’t releated to one particular meterpreter session, so is really necessary to have 2 socks proxy rules? wasn’t already possible to reach network using only one proxy, just from what i understood proxychains command will send packets through the local port to the metasploit framework and then the packet will follow the metasploit routing table that says packets intended to will flow through session 3 which is via then network is reachable via session 1