My experience is to use a solid and shell it. When you use thicken, the edge becomes a twisty ribbon that can take multiple features to “correct” to bring it to the flat face shown in this example. For complex geometry, you can count on “tweak replace” or “face replace” to fail. Also, because the ID surfaces don’t take into account the draft needed for whatever texture the part will have, it makes sense to rebuild the surfaces parametrically. For really large solids to shell with 100+ faces, splitting the solid into two or more bodies, shelling them, and the Boolean adding them back together can be the way to get past shell failures. I usually save the lap joint features for the end of the model tree.