In my personal experience (and of couse very subjective) it helps me a lit to have lines that fit the monitor, and I can have 2 parallel windows. Using 120 chars is for me just too much. I do think the golden rule of typography is “all rules can be broken if you know what you are doing”. For me is a soft limit. If splitting a line makes the code less readable, I do allow more. But frankly, that is the case of one in maybe 50k LOC