[IPSec] Pre-shared key tab

[silviub]

Hello,

I have read the documentation and got a question. https://docs.netgate.com/pfsense/en/latest/vpn/ipsec/psk.html states that Primarily this is intended for use with mobile IPsec, but there are occasional use cases for site-to-site tunnels as well, what would be the cases where this is used in IPSec?
Also, is there any way to run multiple P1s with the remote gateway set to 0.0.0.0? Right now I've got two, and the 2nd one throws errors about no matching peer config found :(

Thank you.