This topic may sound reasonable enough. Things got busy, and we forgot to do this once. When two teams both worked for a single customer, the customer got used to us performing a certain way with them from the first team they worked with. Then when the second team entered the scene, they did not know about these "ways" the customer had already worked out with the first team in their iteration demos. There were a few uncomfortable moments with the customer as they realized we had not cross pollinated these lessons learned from team one to team two.
We don’t recommend you go through that. To avoid it, share the lessons each team learns about the same customer.
While you’re at it, share the lessons each team learns with the whole Lean-Agile approach.
One of the instructional/LX designers suggested having a monthly idea sharing time with all the team instructional/LX designers so they could bounce ideas off each other, brainstorm and talk with other instructional/LX designers. This verbal lessons learned sharing was seen as valuable by most of the instructional/LX designers.