I, personally, am makpid to keep my tallis/tefillin on until after the last kaddish is over. As a result of this, I am always in shul until the davening is over.
Nonetheless, I understand that my schedule may well be more flexible than the schedule of others. I try not to judge other people because, frankly, I don’t know what their situation is. For all I know, they may have a real, legitimate reason for leaving early… and who am I to complain about them?
The Wolf