Padma
I have a hard time shuffling my Daniloff, the longest deck I own. I don't have huge hands, but not tiny ones, either...regular size tarot decks are not an issue, but when we are getting to 14 cm's +, forget it!
Shuffling style has got to be a factor. I've never met a deck I couldn't riffle, because I riffle the corners.
That's a good question. I tried to look at it functionally. Which part of the hand actually grips the cards when held for shuffling? For the smaller decks I hold them with my thumb and index-through-ring fingers to shuffle, so thumb-to-middle-finger would probably be the working measurement. For larger decks I have to hold them with my thumb and little finger (a broader span) so I used that measurement. I'm sure there are charts somewhere.
THIS.i need to go see...
...but i also would like to mention, it is not just the SIZE of a deck that makes it difficult to shuffle, but the thickness and/or overly glossiness of a deck.
Schiffer decks are very thick and glossy as an example--and VERY difficult to shuffle...
I assume you don't have a Mary El ? Or a Sol Invictus... As for the Gorgons... Those ARE rather large even for me, to put it politely (yes, I have the small one now.)Personally I think the card stock of Schiffer is fine and I would be able to riffle it into submission in no time at all...if I could just get my hands around them