In/out play in coupler

Just wondering. Wont the pin, or a bolt people put in, engage before the shoes thus rendering the entire purpose of the joint useless? It seems as if the whole
Purpose of the coupling is to allow a modicum of slippage to absorb road vibration. Which a double pinned coupling would eliminate, putting all the stress on the pin rather than the shoes. Just thinking aloud. Thoughts?
What pin are you referring to?