Magicians (at least card magicians) have a book the describe as their bible. The Expert at the Card Table by S.W. Erdnase. I'm not so sure. Like the real Bible, this study takes various forms.
Most people pay lip service and state how wonderful it is without ever actually having studied it in detail. While this might fuel suspicion that we are looking at an over-hyped reference source, the people themselves can be dismissed as they don't contribute anything to the conversation.
There is also a tiny minority; those that study the book and actually extract practical applications from it. And in between there is a large number of intermediates who can quote passages, and provide guidance but they are really just like high school teachers, regurgitating the discoveries of other people for a wider audience. While high school teachers are undeniably useful, this is less so in magic where the degrees of separation between the individual practitioner and the originator are usually so small that you can go directly to the source without too much trouble or expense. 
The reason I find all this Erdnase/Bible talk suspicious is the general uselessness of the actual Bible. Major religious texts rarely have anything to contribute to modern society beyond interesting literature. Because of the period when they were written and the fact that they got so many things wrong, it's so much work to extract something which is true or correct. And these books tend to be quite long, so you're never quite sure whether it's in there because the author was brilliant or if it just got included by luck. They're suspicious on just a statistical basis. 
So when you hear someone quoting wisdom from the bible, it's more likely this in fact not wisdom from the Bible, but rather this is a wise person who is expressing her own wisdom by finding a short passage that can be interpreted to represent that wisdom. The process is backwards.
Now Expert has two advantages over the bible. First it is more recent and post-dates the printing press, which means we have the original published text verbatim along with surviving first editions to prove it. Second, it is much, much shorter so that it is more difficult to apply the argument of brilliance by luck. But there are still large segments of the book which go virtually ignored today, and for good reason (for example the stock shuffles and large segments of the Legerdemain section).
There is also a tendency to provide undue attribution to the contents of the book. This might be attempted modesty on the part of the student to deflect some of the credit away from himself. I find it more likely it's a feedback process caused by over praising the book to begin with (more attribution leads to more praise leads to more reverse attribution leads to...).
Now, I've spent a lot of time with the book (I'm at least in the 90th or 95th percentile among serious Erdnase fans) and I will admit it contains some very good descriptions of certain extremely useful sleights. But when I hear David Ben speak about the book, or when I read annotated versions by Dai Vernon, they are consistently highlighting certain portions and completely ignoring others. And their insights, post hoc, have coloured my interpretation of the book. Now I'm never sure if I'm reading the brilliance of Erdnase, or the insights of the masters whose interpretation I'm basing my reading on.
And magic suffers a disadvantage from science in that we tend to overvalue original source material. We eschew the benefits of refinement and reinterpretation and keep sending students back to the hundred year old source. This is an advantage in science, where the vast majority of students can become entirely successful without reading the original Principia Mathematica or the original papers on Special and General Relativity (neither of which was written in English). In fact the modern equivalents are far superior because the teaching has been refined and distilled by generations of experts.
Contrast this with Socrates or Plato where undergraduates still resort to the original source material (translation notwithstanding) despite the fact that they were filled with scientific and mystical claims which we now know to be bunk. The Socratic method is really the process that remains after you filter out the metaphysical bunk that Socrates wrote about.
Personally, given the opportunity, I would rather skip to the modern day expert and seek out distilled information. I realize there are practical problems: textbooks are expensive to produce and update for niche markets, and the market for magic is so small that the subset of magicians who are both excellent technicians and competent writers is exceptionally small.
But I can dream, can't I?
 With the exception of the best of the best, most great magicians can still be emailed quite easily and a surprising percentage will actually respond.
 Take for example the ten commandments which are, in practice 30% useful, 70% junk. And that's supposed to be the best God's got.
 I'm thinking of the oft-cited suggestion of "using the nail to reduce friction" that shows up in many handlings of double cards. While Vernon may have used the words nail and friction to spark a series of insights, they bear almost no resemblance to the original (which is not even very good as it takes an unnatural action to get the fingernail into position) so the attribution seems somewhat undeserved.