[barrkel]

Green-field software should be well in excess of 5 lines a day. If the software is old to the point that nobody fully understands it any more, and previous maintainers have left the company, the number of production lines of code added per day may easily be lower than 5.

Older code has a lot more functionality, so every line of code is capable of leveraging more. 5 lines of code in a mature system may do more than 500 lines in a new system. But a bigger factor is figuring out which 5 lines to write. A third of the time can easily be spent researching the code trying to figure out a plan of attack, and the remainder iteratively debugging different variations of 5 lines validating (or invalidating) assumptions made about the code's emergent design during the planning phase.

And I'm not counting test code. Test code is usually cheap to write, if the code is testable. Writing lots of tests is an easy way to inflate lines written, should you be stuck somewhere in the dark ages where they actually measure productivity by such a discredited yardstick.