In the situation
where there are gaps between the panels, make sure you first fill them with
joint compound before applying drywall tape or mesh to the seam.
I believe the
argument on having gaps between drywall panels might stem from the belief that
getting a sliver of mud in between the joints may help to create a stronger
joint seam. However, as long as the drywall is properly secured to the stud
walls, and the gap is less than 1/4 inch, there should be no problem in
obtaining a strong joint seam.