[sharken]

Pair programming is often mentioned as one way to speed up code delivery as review is included in the activity.

But as you put it, any non-trivial task, e.g. where you're creating multiple new classes and refactoring along the way is hard to do with pair programming.

[username90]

The review you do when pairing isn't a proper review though. The point is to have someone who wasn't there during implementation look at it, while with pairing both people will have similar biases about the code.