I do not have all the answers when it comes to editing, I am always honing my skills and looking to improve. I continually realise that less is more but you still need enough, or what's the point? I have more answers than I did. I would say I edit on feel, I am sure that I would edit 20 different photos in 20 different ways on 20 different days. I would like those photos more today than I would have a year ago.
Selecting images for black and white is sometimes immediate, I see it and think "get rid of the colour", sometimes I don't feel like I am getting enough from an image so I try it out. Some picture I take knowing I'll go black and white. Like I said, I edit on feel.