Your applications contain 20-30% dead code that is never executed. Not just commented-out code that programmers have left in “just in case”, but routines never called, branches never executed and screens never displayed.
The cost of software maintenance depends on the size of the code base, but systems with dead code are more expensive to maintain. This is because every time a developer comes across a dead piece of code, he becomes unsure: “I wonder what this does? Is it executed at all? I better investigate some more.”
Dead code causes simple 1-hour maintenance tasks to ballon into futile multi-day code archeology expeditions. Don’t allow dead code in your systems.