I am embarrassed to say that I don't clean my machine as often as I used to. I am one those who never matches their thread to a project, as I use only white, taupe (dark and light) and black thread colors. I wind a lot of bobbins with my Arifil thread and really don't get much lint in the bobbin area.
However, I do keep an eye on the lint and if there is any lint I clean the area immediately and then put just the tiniest of drops of oil in the bobbin casing where the metal bobbin wears against the metal casing. You should always use a tiny amount of lubricant (oil) where there is metal to metal.
I have my machines cleaned by a professional once a year whether they need it or not. So far, (knock on wood) I haven't had any problems and I have been sewing since the 70's.