Originally Posted by
Onebyone
I do both. Whatever the seams wants to do is how I press it. Sometimes I don't off set, sometimes I have opposite seams on both ends. I let the seam twist in the middle. I've never had a problem with machine quilting no matter how the seams are pressed. I haven't noticed any needle holes or skipped stitches. I do stitch in the ditch with open seams. No one has ever said I noticed you did SITD with open seams, even in judged shows. I guess it's what you do with what you have the way you want to do it.
OBO are you using a longarm or domestic? the difference in needle size between the two is what the OP was concerned about and what my comment was referring to. The size of a LA needle is much bigger than a DSM and can break the stitching threads used in piecing if longarmed directly on them. With a domestic you can probably get right in the seam line if seams are pressed open and not do any damage. With a longarm there is the potential for breaking the stitching lines so most show quilters I know will stitch a thread or two next to the ditch as there is no ditch when seams are pressed open (ie a low side of the seam) . Breaking the piecing stitching may or may not happen but we will err on the side of caution and not stitch directly over them. In a big national show ditching that is right next to the seam even by a thread could mean the difference between ribboning or not and it won't be noted on the judge’s comments. The judge doesn't care how the seams are pressed either, unless there is obvious shadowing, what they are looking for is if the ditch quilting is "in" the ditch, directly on the seam line and not a thread or two over. In most cases a judge can't tell if the seam was pressed open. The longarmer made that decision based on what he or she saw before loading it on the rack.