I was working on a 1.7k LOC file as I read your comment. To be honest I'm not sure I understand the question (how would splitting the file into two change anyth

I was working on a 1.7k LOC file as I read your comment. To be honest I'm not sure I understand the question (how would splitting the file into two change anything in your view?), but one thing that I find helpful in general is my editor's ability to collapse method/class/etc. definitions. That lets me work on the function I want without being distracted by other definitions. Perhaps that's the answer to your question? But that's useful at 200 lines too, not just 2000 lines.