The programs I have seen have one awesome amount of nested conditionals. So the problem is that from any given point of disruption we could have a very long way to go to get the parser back on it's feet. In this regard I am saying that our underlying concept that hand coding the parser is inconceivable represents a major issue. The issue is this nieve paradigm of smooth hierarchical topologies. That is simply not what is out there.
Many programs contain serious syntactic disruptions.
Trust me, I am not at all sure. But the presence of the stack seems to mean that a heavily nested source image might have the latter portion of its text processed more successfully, because we will still have something around to glue the recurse-exiting clauses when we get down to them. But I emphasize that the attempt to glue something is distinct from merely recognizing and syntactically understand it. The tools do not keep that distinct. The hierarchies destroy the distinction.