Level Up (A5E) Quick question about heralds and paladin subclasses

[lichmaster]

IMO the main upside of adding a school to your spell list is extensibility: if a new supplement comes out with a spell from that school, you can start casting it right away (unless the DM prohibits it for a very good reason). Having 2 specific spells prepared gives more moment to moment freedom, but less variety and no automatic extensibility