Elsewhere in this thread it's mentioned that Google makes use of large-scale, automated refactoring tools: http://research.google.com/pubs/pub41342.html

Would be interesting to know what percentage of the total LoC touched are typically from that kind of automated refactor. Depending on the codebase, you can touch a ton of lines of code in a very small amount of time with those tools.

I write between 4-600 lines of code a day where I work... I feel that 120 LOC is a day is on the smaller side (of what I'm used to anyway).

It really depends on what you're writing. Lower level c / c++, doubtful. Python, javascript, java, etc, yeah, it's believable.