I would never consider transferring a "working" deck except as a specimen for a collection or maybe a keepsake. My main deck is as intrinsic to my card reading as Willie Nelson's beat-up guitar "Trigger" is to his music. In both cases, it would be unthinkable to sever the connection between the practitioner and his long-time instrument.
In my experience this isn't just a matter of superstition or sentimentality. The handful of people I've known who were adept card readers (using the Tarot or regular playing cards) all used a jealously closely-held deck dedicated to that purpose.
My father was an uncannily adept poker player whose reputation (spanning a circa 100-mile radius in the gambling underground) was such that a fresh deck of cards had to be opened once he sat down at the table. At home, he would sit and play solitaire, etc., for hours on end so as to study the cards and how they fell. I suppose I inherited or adopted a certain knack for studying and knowing cards from him.
However, there was a significant difference between our card activities. He was studying the patterns among the cards' meanings in the relatively closed context of a game, so the understanding wasn't specific to a given deck. I, on the other hand, was studying patterns and meanings in a more open-ended context that depended more on the specific deck I was using.
My point is that the best long-term learning about the cards comes from studying and using them.
In my own case ... I was on the road doing the full-time rock musician thing. This particular road stint occurred during what can only be called a major life-shifting existential odyssey. I purchased the Rider-Waite deck on a whim, then set about learning how to use the cards. Over the subsequent years I read quite a bit about the Tarot and accumulated a number of books on the subject. The biggest thing I learned from years of study is that there's no solid consensus on the cards' origins, history, use(s), and meanings.
I therefore used the books (etc.) as background "serving suggestions" from which I derived my own knowledge base with primary regard to using the cards. This knowledge base included my own conclusions about certain issues (the deck's origins; which cards were to be used; layout preferences that worked best for me; etc.) based on readings, study, and practice. I settled on a praxis that worked for, and made sense to, me. YMMV ...
The significance of a given card doesn't derive 100% from the card in isolation. It's also dependent upon the layout / spread being used. As a result, the layout protocol is as important to developing rapport as the cards themselves. If you stick with the cards, sooner or later you'll settle on a preferred layout / spread. I've never met any adept card reader who admitted to using more than a couple or maybe three spread protocols. I've tried a number of spreads on an exploratory basis, but I settled on a single one early on.
I'd therefore recommend using "book learning" or "instruction" to get started, but only for starters. The diversity of opinions and attributions prevents such documented sources from providing a guaranteed "full education". A "cookbook approach" is useful for getting acquainted, but it will never get you past a cursory beginner's status. At some point you have to learn from using the cards rather than just reading about them or discussing them with others. In the long run, the only expert you can trust for guidance is yourself, and you'll have to grow into that expert status by developing confidence in what you glean from practice.
