It depends....if the mobbing is what my former agile consultants were pushing (having everyone from dev's to business analysts do it) then no, it doesn't work.

It depends....if the mobbing is what my former agile consultants were pushing (having everyone from dev's to business analysts do it) then no, it doesn't work. The few places that I have seen it work sort of well is when there is some big issue going on such as a production outage that can be benefited from having a group of devs together looking at the issue. Aside from that the level of engagement goes down the more people you add to the session and it felt to have diminishing returns on the quality to developer count ratio.