I write a comment any time I think there's something that won't be obvious if I come back to it in a week. Also to break up a long structure into logical chunk

I write a comment any time I think there's something that won't be obvious if I come back to it in a week. Also to break up a long structure into logical chunks, especially if the procedure is longer than a page. When I start a function, I might write a couple comment lines about what it will do. Now I have a checklist to use as I write it, putting each bit of code under the line it's related to. So to answer the question: I comment all the time, but notes, not essays. Hints here and there to make reading or remembering quicker.