I read a training guide a few months back which took some examples similar to this and went on to deduce that longer rests between working a body part were all part of a good program. Rookies could do whole-body workouts three times a week but a more conditioned lifter needed a week to allow a muscle to recover. An elite lifter could require two or even three weeks to recover properly from a workout. He went on to say that some of the athletes he trained would only work a bodypart every month or so and were making better gains than they ever had. You can probably guess that he didn't get my $50.
Before I stumbled on the madcow 5x5, which was before the monster thread existed, I used to take a week off every four to six weeks or, at least, have a really light week. If I didn't do this I'd start getting muscle pulls and assorted pains. I almost always found that I came back refreshed and stronger. I also found that my appetite went through the roof.
The next stage is optimizing the periods between deloads and making the most of the deloading phases themselves which means getting a good program. I'd recommend taking time to read through some of the many articles on dual-factor training. They can be a real eye-opener. Madcow links to some of the best on the contents page of his 5x5 program.
Edit: I should read prior posts before waffling on. His links here are to dual-factor proponents.