Threshold setting
Clean inputs, documented outputs.
Scope is settled in advance so the size is never a surprise. Values that look plausible but cannot be sourced are dropped. The limits of what exists are named rather than glossed over.
Overlap reporting
Where segments share records, stated rather than double-counted into a bigger total.
Second-opinion pass
Having somebody who did not build the file check it against the brief.
Whitespace discipline
Removing the invisible differences that make two identical values compare as different.