How important is punctuality?  If you are attending a meeting it may or may not be essential, depending on your role.  Catching a train in Switzerland being on time is critical.  What does it do to the moral of your team if there is a habitual late arriver?  Does it matter?  Do you notice a change in the chemistry of the group when a frequent later arriver offers a half-hearted explanation.  Or are you happy they attended?  Sometimes little distraction keep us from the most significant areas of focus.  If they are not addressed they can be the nail that loses the war.