I use the newest one pretty hard-core for the first week or two of owning it. At the end of that time, I usually have a sense of its "place" or perhaps a better word would be "niche", so it joins the rest of the collection, secure in the knowledge that it won't be forgotten
. That is, the good ones. Others . . . well, they get forgotten. For now.
Some, like the Inner Child cards, don't even get a tour of duty. But others, like the MerryDay, are the mainstay. Then there are ones that I *save* for special readings, like the Babylonian, which gets used only on deep-seated issues of personal growth. I'd even be inclined to refuse a request with that deck, because it's very unapproachable unless I have a *serious* question for it. Those readings take days, when I'm usually a lightning reader, throw the cards, read it, get it done. I'm not usually the type to have a spread lying around for days - except with that deck.
So, back on topic, mine overlap, lots. But each one usually gets a week, then the cream rises to the top
\m/ Kat