I have found that pairing works well for teaching and for solving particularly tricky problems. It also results in higher quality code than working individually

I have found that pairing works well for teaching and for solving particularly tricky problems. It also results in higher quality code than working individually with reviews afterwards. However, it is a fair bit slower than working individually - depending on the type of work 0.5x - 1.5x a single dev. That said, the outputs are of a quality actually unachievable with a single dev, so comparing time doesn't always make sense. So, like many things, it is a tool that should be used when you feel it helps. For example, API design can be done well in pairs, where the code quality has a big impact later on, and then the functionality implemented individually. It also is a great tool to speed up your onboarding process and get new devs giving useful feedback from day 1 and being highly productive within a week or 2.