My regular climbing partner has been down for two weeks with a wrist injury (from climbing) so I've been climbing with all sorts of different partners - basically anyone I can find who has a pulse and can hold the belay rope. This got me to thinking that you learn the most when you are out with people who are either better than you or worse than you.
If you climb/ski/mountaineer with better climbers/skiers/mountaineers than yourself you can learn an enormous amount from these people. Similarly, if you climb/ski/mountaineer with people who are less skilled than yourself, you get pushed beyond your comfort zone and have the opportunity to learn a lot too. Simply being fully responsible for leading every pitch, doing all the navigation and route finding, assessing stability, and making every single decision that has to be made in the course of the trip can be a huge learning experience.
Conversely, we learn the least when we recreate with people at about our own level of ability. In these situations bad habits, poor decisions, and sloppy skills often get reinforced as neither person has the expertise to correct the other.
The caveat to all this, of course, is that you are actually open and willing to learn, and, that, of course, is the hardest part. Most of us prefer to think we know everything. But be careful, you could be suffering from the Dunning-Kruger effect.
Route-finding on a KMC trip up the west ridge of Mount Kitchener