I think you are also misunderstanding hoe the software development lifecycle works. You don't just bash out code from A to Z and everything you type makes it into the game. You have to refactor. You have to optimize. It may be that one language requires less lines of code to do a task but at the same time if there is a bug it could be very tricky to locate it. Or that one language has infinatly more options available. There is also the issue that there is literaly tons of good game programming resources available that are written in C or C++.
For me a productive day usually means that I remove lines of code from a project and not add them.