I agree. That is a very common problem that I see on forums. Especailly on internal beams in which the end forms just hang out there and are pulled off center by strips. At least on external beams, the end forms can be supported on center with something underneath to keep straight.

And if you are tracing patterns from a full sheet, then a pencil line here and there can add up. With full size patterns, we have to trust the sofware and printers to be accurate which I believe is more so than making a set of patterns and then tracing those. Every step adds a chance for errors. When I was doing more teaching, I always suggested that the paper and forms and lines can be correct and you end up with a crooked boat or you trust your eye when building that things are fair and natural by following your instinct. So if waterlines and centerlines are not dead perfect, I would move on and make adjustments when things don't look right. Hence, I go with external beams in which a form can be adjusted and even removed to correct after the few strips are on the boat.