Yeah, fortunately they don't appear to actually enforce that regularly through technical measures. As a researcher with legitimate paid access (via my institution) to JSTOR, it would be absurd if this were enforced. If there is a special issue of a journal exactly in my research area, I pretty much need to read all the articles in it, or at least skim them. To comply with the terms, do I really have to choose an article to avoid reading, so I only download (N-1) of the articles in the issue?