Art Director tip: You can prevent tangent lines by adding a lighter secondary stroke around the foreground characters. (Example: Action Comics 1034, Christian Duce.)
Without this outline, the panels would directly intersect Superman directly, which may muddle the perspective. Most often, I see this technique with a light stroke alone, without an extra black line as Duce has demonstrated here. Either is fine, depending on the job.
Image Description: Close up of Superman. His pose breaks through his panel and overlaps a bunch of other panels. A light outline around his body prevents the lines of those panels from intersecting him directly.