10 lines per developer day - this is so outdated it should be disregarded entirely. Not much is gained from writing articles around this "10 lines a day" assertion unless you're writing something about computing history.

Maybe this was true when people were writing operating systems in assembly language - which is the time and context in which The Mythical Man Month was written.

Lines of code per day really is a pretty meaningless measure but having said that there is at least some truth to it, in that any developer who is writing a typical 21st century application and getting only 10 lines of code per day written, should really examine if they are in the right job.

People misunderstand it. It means writing code, documentation, testing, bug fixing etc.

I'm not sure it is that far off over several years. If you look at Google, and say there are 52 * 5 days * 10 lines of code, 2600 lines of code per developer. Extrapolate that to 20 years times how many developers and list on code that is currently used, would it be that far out?

People over-estimate the sustainability of short term coding lines per day, versus multi-year coding.

Here's an example: https://github.com/sumatrapdfreader/sumatrapdf is code written by 2 people (me and another guy).

It's written, documented, tested and bug fixed.

It's 110k lines of code. And it's tight. Good luck removing 10k lines of code and not loosing any functionality.

Assuming 10 lines per day and round-the-clock 365 days of working, that's 30 man-years of work. 15 years for 2 people.

I didn't spend 15 years writing it. It's a part-time effort over 10 years.

The 10 lines per day is off by at least an order of magnitued.

And I don't claim to be spectacularly productive. Jonathan Blow wrote 90k lines of code for Braid in 1 or 2 years.