[NyteSky]

Tolkien of course did it excellently. I personally would have preferred it if he alternated a bit more often, but that's not a big deal either way. Actually I've found that many authors, and most of the better ones (in my opinion) use interlacing. I think it works quite well, usually. The trick is keeping both interesting and keep them a good distance apart but not so much that the reader loses track of what's happening. When used properly, it helps a great deal I think.