[softbuilder]

This pretty much nails it. Pairing is a tool in your toolbox. It's not something you should be doing 100% of the time.

I did take issue with two points:

>I can certainly understand the argument that you should be learning things like that in your own time anyway.

No! If you're using a new tool for work, work-time is when you should be learning it. And learning in a pair can be great. It takes patience though. Research, OTOH is harder. It's a lot like reading a book at the same time. Often a strategy of "split-up and regroup later" works well.

>In my experience house cleaning tasks such as investigating why a test is ‘randomly’ failing on the CI machine are less likely to be looked at if everyone on the team is pairing 100% of the time because it interferes with productivity of a story.

You fix this by making those tasks their own, smaller story and throw a pair on it. This is independent of pairing and is more closely tied to your overall process. A granular system like kanban (which has its own problems) shines here.