I make a lot of charity quilts that are tied and we always use 1/2" seam but we keep the patterns simple -- strips or large blocks to minimize the bulk at intersections. We do this so the quilts won't fall apart and it works well. As Tartan mentioned, using 1/2" seams when doing blocks with a lot of pieces would create too much bulk. (When I was learning to quilt, I cut the pieces with 1/2" seams and then trimmed them to 1/4" (I was concerned about all the bias edges) -- I quit doing that because of how much time trimming seams added to the time it took to make a quilt.