JKR doesn't understand consistency very well. That's why this thread "needs" to exist.

 

It doesn't need to exist. Mostly because it already exists in quite a few other forms. Half of the problem is that people confuse fanon with canon or they think the only way you can be a powerful wizard is if you can regurgitate loads of facts and know a crazy amount of spells. That's not a problem with the books though.

JKR definitely has some serious inconsistencies at times, but it isn't nearly as big of an issue as people want to make it out to be.