[prometheus76]

If you pair two top performers, they get slowed down by 10-20% because they each have their own way of approaching the work, and there's usually conflict as they are each convinced of their own way. They work even faster, however, if you put them next to each other, but working separately. They watch each other and start tacitly competing. You'll get another 10% out of them generally.

As for pairing the two lowest producers, they'll sink even more as they are confused by what the other person is doing and it slows them down.

Changing someone's level of productivity is essentially untrainable in my experience. It's not a training issue. The people at the bottom know how to do the work, but any attempt to show them a more efficient way of doing it is overwhelming and confusing to them, and they shut down.