It's not just the number of characters, it's the size and the font. Even fixed-width fonts differ greatly in their readability.
I can handle different line widths just fine up til about 120 or so without losing the flow of the program, but some fonts simply make it more difficult at any width. I've tried many, but for some reason I keep coming back to Courier10 at 10 points. I'm almost embarrassed that my choice is such an old and primitive font, but that's how my brain works. In my experience, if code is well-spaced, well-commented, and broken up into logical groups with appropriate blank spaces, line length can be about 3/4 the width of whatever editor is being used. And most editors are wide enough to easily accommodate over 100 characters. -- http://mail.python.org/mailman/listinfo/python-list
