This is a great thread. Back before I knew anything, I trained on an empty stomach. I read and considered my situation and now do what I can to get something in the gut before I train.
I work out at 5:30 am (getting up at 4:50 most days), so the whole "meal 2 hours before training" has never been an option.
I take 8 oz of OJ with a scoop of whey as soon as I wake up. I drink a little under a litre of water while I train. If I am doing cardio after lifting, I typically drink/sip less water as it tends to make me nauseous to have so much liquid in my stomach.
Afterwards (my gym is a 2-4 minute drive from home), I have 8 oz 2% milk with 2 scoops of whey and (new) tablespoon of olive oil. I agree with Carl that I don't think this post-WO shake has to be taken the second you stop training. I try to make sure I have it within 30 minutes or so, but usually have it within 10 minutes of being home.
Then, I have my other meals of the day: 7:30 breakfast, 10:00, 12:15 lunch, 3:00, 6:30 dinner, 8:30 snack. I always fail on this during the weekends with kid commitments and running around, so I typically eat fewer bigger meals.
To the 24-72 question. I do feel like I notice the difference on a workout day when I have under-eaten the day before. I see this especially when I train my legs.
MC, who rambled a bit here. OY.
Complication makes it easy to explain failure.