Sure, one of the best examples was in this thread.
If you create a model that has two shells which exactly touch each other, then the math involved in generating a slice through the plane where they touch gets rather squirrely. Some raster lines will manage to sneak between the two shells, while neighboring ones won’t. The artifact you get looks a little bit like layer lines, but it is usually quite a bit worse, and it is often only on the “downwind” side of the coplanar section.
As I said earlier in this thread, you want to avoid this, even though it’s only going to bite you when a layer of your print happens to hit the coplanar section. The “best” way to avoid it is to union the shells together in your CAD program. That way there won’t be any ambiguity about what’s supposed to happen in that area. If you can’t do that, then the next best trick is to push the two objects closer so that one actually sticks a tiny way into the other. PreForm will do the right thing in this case. It will laser the area inside both shells exactly the same way it will the areas inside either one of the shells.
I looked for this in this case because I often see people make this type of object by setting the text characters exactly on the plaque. But that’s not the case here. In this case, the text is in the same shell as the flat area behind it. The only place in this model which has this issue is down in that gutter around the outside.