Every building or structure exit must be arranged and maintained to provide complete and?

It is not clear just what the question is trying to ask. Stadium exits are often obstructed by a column for the purpose of guiding people to prevent a mob from blocking the egress. That contradicts your question, but is the superior way to assure safety when evacuating a building.

But it is quite difficult to write that into a law. So what exactly are you trying to ask?