Can you elaborate?

Is this pairing on small tasks that get done in (less than) a day? Or do you also have longer-running implementations (a few days, a week, or maybe even more?) where you rotate the people who are on it (so one task might have had 5 or 10 people on it during the implementation)?

If the latter, that sounds very curious and I'd love to learn more about how is that working, how do people feel about it, what are the challenges you've seen, and what are the successes? It'd be great to see a write-up if you've had this running for a longer time!

If it's only the former (smaller tasks), then this is where biases and assumptions stay (within the scope of that task): I still believe this is improved with an independent reviewer.

I do have a blog post about this sitting around along with all my other mostly completed posts. Finishing this one would be great as it's a topic I'm very passionate about!

Our stories were broken up to take worst-case-scenario 5 days, the ideal was 1-3, of course. Maybe would be multi-day stories so yes, if something ended up taking 5 days it was possible the whole team could have touched it (our team was only 6 devs so never more than 6).

In short, there are the usual hurdles with pairing, the first one being that it takes some time to catch your stride but once you do, things start flying. It is of course not perfect and you run into scenarios where something takes longer because as a new person joins the ticket, they want to tweak the implementation, and it can get pulled in different directions the longer it takes. But this also gets better the longer you keep at it.

There are lots of pros AFAIC but a couple I like: you develop shared ownership of the codebase (as well as a shared style which I think is neat), ie, every part of the app had at least a few people with lots of context so there was never any, "Oh, Alice knows the most about that part of so let's wait until she's back to fix it" kinda thing. There is no "junior work." When a junior joins the team they are always pairing so they ramp up really quickly (ideally they always drive for the first several months so they actually learn).

Another downside would be it's bad for resume-driven-development. You don't "own" as many projects so you have to get creative when you're asked about big projects you've led recently, especially if you're happily in an IC role.

And also yes, if there is a super small task that is too small to pair on, we'd have a reviewer, but often these were like literal one-line config changes.

We'd also have an independent reviewer whenever migrations were involved or anything risky task that needed to be run.