I kind of disagree.... Well not entirely...... Sort of...
I have a sense that if you´re really keen on tarot and really serious about studying it, I see that a wide familiarity of varying degrees can only enrich your understanding. I alternate constantly between learning/ studying/ enthusing about / reading with / chopping and changing the RWS, Marseilles and Thoth.
But when I just want a good old spontaneous reading, something that reads effortlessly, I go for the RWS (either Universal Waite of V. Romantic or BG or Klimt).
But Im conscious at all times that these systems feed off and derivate from each other anyway, so once you start exploring the universe of one, it helps you with the others.
The Thoth challenges me and sometimes I get exasperated and give up and go back to my RWS-based ones. Then The urge comes creeping back and a couple of months later, Im back with my nose in the Thoth. And this chopping and changes is constantly throwing light on everything else.
I kind of see a knowledge of each system as a pretty sound basis for any student... In my my own mind, I see the Marseilles as the equivalent of Shakespeare, The Thoth as James Joyce (impenetrable at times, but ground-breaking and challenging) and the RWS as .... I don´t know. I haven´t thought of an analogy yet... With these under your belt you can read just about anything...
But as others will rightly say; if studying becomes a chore or something you feel you HAVE to do, it isn´t a pleasure... and ain´t worth it...
By the way, I have a Radiant RWS up for trade if you don´t want to buy it...