You might want to check wing panels for accuracy by sticking a short tube between the panels, bringing them together and taking a close look at the whole wing. The tips must be tracking identically or you will have problems.
I'm an old, Old World, European, where even now, many pattern models have a one-piece wing.
The age-old advice,when joining the panels,was to make sure that the tips were aligned perfectly parallel to each other(spirit level,incidence meter,whatever), and "lose" any discrepancy at the joined root.
The other bit of advice was,if there was more than about 2-3 mm discrepancy at the root; bin them, or return to sender...