We are a graduate school running a separate 365 tenant from the undergraduate campus so our use case is not exactly the same.
They also have Yammer enabled for all users but no specific adoption plan or use cases they are pursuing so that network is pretty spotty.
In our case Yammer is the official source of information from a number of groups (clubs, departments, research centers) and groups that are actively managed and promoted get a predictable level of activity. Overall the network has many users who are readers, not posters.
Since the network includes students many business related groups are private which limits some of the "work out loud" serendipity that is possible in a network at a company.
I would say Yammer meets the need technically but struggles at times culturally. We get a certain amount of fatigue over the sheer number of communication channels (Outlook, Yammer, Teams, etc.) and even though Yammer was introduced to help reduce email volume the students who advocated graduated years ago and current students will ask why we don't just email them everything.
We've reached an equilibrium where some things have a home in Yammer but everyone still gets too much email.
-Geoff
