Unless you're travelling a massive distance you will still be within the same geo-ring fence for your IP range. Locked IP does not mean you can only connect from the same router in the same house.
For instance my IP range would flag as Lancashire, UK. If I attempt to log in from any IP within a set radius of that location it would accept it, if it's too far away from the registered location it would lock the account, and require email verification to unlock. The account would subsequently be flagged for review by the servers GMs. Every time you log into the server you're required to enter a 2FA code that's sent to a mobile phone (text or authenticator which evers easier). Putting both of these features in place massively hinders account sharing and reduces the number of multis.