The article is interesting but I don't think we all do, should or can train 5 hours a day, every single day. As a consequence many statements that sound quite general in scope, could be easily taken out of context.
Also if you're doing 30-50 reps every day for 6 days a week, I would expect your "max out" weight to be different from the one you would get by doing 45 reps a week.
BTW I do hear this...
How You Feel is a Lie
That phrase is the Broz mantra. You simply can't listen to your body because it's lying to you. Broz can cite countless examples of athletes setting PR's on days they didn't even want to train, as well as days where the athlete felt like a million bucks but didn't fare so well in the gym.
...quite frequently, and I knew this to be true(-ish) from my previous life as a runner. You can feel like crap and perform well, and the opposite too, even when lifting. However there seems to be two types of bad days, and I still haven't found a way to tell the bad days that truly are such apart from the ones that turn out to be better than expected.
The truth probably lies in the middle, i.e. you should not back off just because you woke up in a bad mood, but you shouldn't push too hard day in day out either. But I don't think there's any way to tell what "too hard" means other than paying attention to how your body feels and some trial and error.
There are also two types of trainees, the ones who don't push hard enough on a daily basis (besides slackers, women also tend to be rather conservative), and who probably benefit from this advice. And the others who have a habit of always pushing the envelope, who shouldn't blindly following it.