Figured it out. There simply wasn’t enough geometry. A loop cut where each elbow and knee should be and reassigning the vertex groups worked a treat.
Thanks to your post, I was able to solve the problem I was having with my cube dude. Initially, I couldn’t get the limbs to bend at the elbow, knee, wrist or ankle because there weren’t any vertices for the armature to link with.
After seeing your post, I removed the armature modifier and then, after adding loop cuts at the joint areas, I was able to get reasonably good linking with my mesh.
Because all my limbs are a contiguous mesh with the torso, there’s some noticeable mesh distortion going on (especially around the shoulder area). Adding more loop cuts in that area distorts the UV mapping, so that’s probably something to be aware of during character construction.
