There is one standard way to cast fireball - it works, it's cheap, it very rarely backfires, it's in all the textbooks, everyone knows how it behaves - but sometimes you sit down in a tavern next to another wizard and you just know before they even open their mouth that they are going to spend the next twenty five minutes telling you about how they learnt this alternative way to cast it and it's taken a bit of practice but they can just about cast it as fast as they could before and how it's so much more ergonomic or whatever