Leaf storage has everything to do with the size and shape of the table. For example, a round table cannot store leaves because of the shape, nor will our trestle tables where the leaves are put in on the ends instead of the center.
The majority of oblong tables will store them with ease. The most leaves you can store inside a table is four. They sit side by side, and then two on top of them. When all four leaves are stored, two of the leaves will not have a skirt/apron on them so they store easily. You do not have to store all four leaves inside a table if you would rather have all four leaves have a skirt/apron on them.
If leaves are not stored within the table, they should be stored at a similar humidity. For example, storing the leaves of your first floor dining room table in a basement will make the leaves susceptible to wood movement that differs from your main floor table. This is because there is a drastic change in humidity and that affects the wood. If this happens, please start storing your leaves on the same level of the house or in an area with similar humidity and it should go back to normal over time.
It is also a good idea to put your leaves in your table once in a while so the gears and slides on the table see some movement and the leaves can settle into the table. For example, if someone buys a table with leaves and goes 5-10 years with never putting them in, the mechanisms on the table can be a little stiff. Putting your leaves in, even if briefly, once a season is a great idea to keep the mechanisms in working order.