Pairing for designers is an amazing tactic, but not without pitfalls. It's super good for generating ideas together and talking through design decisions in the moment, as well as course-correcting if someone is getting off track. It's great for relinquishing the silos us designers usually fall into. I do think there is a time and place for it though, not always. Too much and you might end up not pushing the boundaries as much as you would have had you separated and then paired after for feedback. Ie. Can't have too much of a good thing. But overall, I like it, it's great. We have product designers at our company who lead features and then will pair occasionally with other designers when a design jam is needed.