Plenty of my classmates studied using only FA and passed, because that was the "advice" passed down to them from upperclassmen. And these weren't the top 5% of the class (obviously) who could breeze through it anyway... these were average at best students who really just wanted to pass.
Sure, they weren't so smart for listening to that advice, and could probably have done better with a more rounded resource suite. And sure, the upperclassmen who passed on that "advice" were equally "not so sharp" for following the same advice and then passing it down... and were also of the average at best crowd just wanting to pass. And sure, they didn't spend a week with FA but like three months agonizing over memorizing it. And they probably didn't kill the boards by any measure... but I don't know of any personally who actually failed.
I suspect that when FA wasn't clear they probably reverted to class notes, which happened to be pretty good at our school. So this really isn't evidence of a "what to do in 7 days to 'just pass' strategy." But as far as "no one in their right mind" using just FA... it happens. A lot, apparently, at least at our school and one or two more where friends attend.
Perhaps there's something to be said for the students who struggle to retain this mountain of information for long periods of time and integrate it all into a big picture. Being overwhelmed with multiple resources may not be much better if any than sticking to one somewhat incomplete and short on explanations resource, and knowing it as well as possible. It does seem to at least offer one strategy to passing the exam. Who knows if those students would have scored lower or higher using more/different resources, but "just FA" accomplished their mission.
In my case, personally, nothing raised my UW percentage more or quicker than the first pass through FA. There was about a 10% average increase in test scores from the ones before to after that initial read through. I was a good student, though, and missed a lot of UW questions early on because of a forgotten detail or name that just needed refreshing. I suspect that other good students could probably pass easily with a couple of trips through FA (doable in a week) without problem. Of course, many of these students might well "just pass" without any study at all, but I think that would probably qualify as "not in their right mind", even for me.