When I first became interested in tarot, I used one deck for the first year and a half. I knew there were other decks, but not that there were so MANY. Then I found AT and really began applying what I had learned and experienced with the wisdom and experience of others.
I found that I enjoyed comparing decks and cards and was also hoping to find a small handful of decks that I seemed to feel most drawn to. I learned quickly that what looks good on a computer screen may not appeal to me in hand, and so I started buying... I do have a good base now, and most of my other decks have been kept as well because I do love the variety of them. All of my decks are wonderful to me, and I DO read even with the decks that I don't "click" with because I want to be able to read with anything...
But I've pretty much quit buying now. First because I've perused what's available a thousand times now and the ones that really appealed to me are either already in my collection or hard to find, and also because I'm comfy now and hunkering down with the ones I've got. An occasional new release or a super deal on an OOP gets picked up once in a while, but for the most part, I'm cool where I'm at...