Brian, I hear what you're saying about cheap paper. I constantly use copy paper, and I could care less. If I didn't use it to sketch some of my ideas on, I don't know how I would survive really. I render stuff on better paper, of course, but I will start out on scrap paper, or little sketchbooks, which are so small, I just use a pen where I make severely messy gestures. I also have a tremor, so those look pretty awful.
I've kept most of my preliminary sketches on this paper, from as far back as 35-40 years and so far, absolutely nothing has changed about them. No yellowing or anything like that. No breakdown, and I wouldn't care if they did anyway, they're just ideas.