You’ve always been able to manually create stacks (that’s the whole point of the app), manually create a single stack and to scatter the cards with a menu option but now you can also bring all the cards together into a single stack.
The app has become popular for many uses including education. People use it for all kinds of categorization, brain storming, teaching, research, planning and all kinds of sorts. Sometimes its useful to shuffle and scatter the cards to be sorted and sometimes it is less distracting to put them in one stack and sort the card on top.
I hope you enjoy this new flash cards style feature.