Recently I convinced my team to give it a try before a release and they were really happy and confident in what we were about to ship. The first time I tried mob testing was for a short mobile app contract, several of us would jump on a zoom call with our tablets and test the app.
The session would usually start with people chatting and cracking a few jokes to lighten up. After that, they usually would leave it to the tester to figure out a rough agenda for the mob session. During those sessions, we bounced ideas off each other and found edge cases that single-person testing would miss, or it would take a lot longer to find.
Personally, I wouldn’t use mob testing for checking over every single new feature, but, it works pretty well for pre-release smoke/sanity testing.