Doug
I do not think that is a valid "scenario". I believe this is an FAA ruling, but I could be wrong.
At PDT we had a reserve 'start' time. 15.5 hours from that time you were a pumpkin. That prevented scheduling from doing what you describe. Technically you are on "duty" since you are on call at home.
Not really important to this thread, and I will be damned if I can find the ruling from the FAA.
Oh, there are ways around this, trust me. For example, my reserve start time is 7 AM. I get the call at 8 AM "We have a high speed for ya in DTW tonight, so we're going to DH you up there late this afternoon. In the meantime, you're released to get your required rest. We'll call you later with the details." Not nice, but totally legal in the eyes of the FAA and the pilot contract. So, I was aready awake with my kid, and NOW I have to take him in to daycare, come home and try to go back to sleep, yet I still have to get a phone call notifying me of not only my show time, but where the hell I'm going that night. This is legally called "rest."
Like was mentioned previously, I'm normally okay on the 1st leg after a CDO (mainy b/c I'm just delerious from sleep deprivation). It's some of the reduced rest overnight, I think, can be worse. With CDOs, you can't go over 15.5 hours of duty, so they more or less have to release you when you get back. If WX is a factor on both ends of the CDO, you're screwed, though. On the reduced rest overnights (let's take DEN for example), the hotel can be (and IS in DEN) about 30 minutes from the airport. Well, you just lost an hour there. It takes time to get ready in the morning and un-ready at night, so we'll call that another 45-60 minutes. So, you're looking at a 6 hour night's sleep if you're lucky, which is often bookended by 5-6 leg days. Ask me how useful I am on that 6th leg the second day.
I think rest periods are one of the serious problems in the airline industry today. 8 hours of rest does not mean 8 hours of sleep. A pilot should never have to make the decision b/w "Do I eat when I get to the hotel" or "Do I sleep when I get there." Both are essential to functioning in a highly alert state.