Real railroad yards are not so much for storing cars but more for making up trains of cars. Stored cars aren't making money, ya know?
The thing is, the answer to your question lies in the purpose of the yard.
If it's a drop off at an interchange or a small yard to service a smal industry or maybe a small-medium customer, then there will be less sorting and more larger blocks of cars or whole trains picked up and dropped off.
If it's a small yard for dropping off cars for a couple of locals to pick up and distribute cars through the branchlines then there will be a lot more sorting going on.
There's a website that helped me understand yards a lot better that I can turn you on to. It's here and esspecially this page.
I am thinking about doing a small "training" layout to get some hands-on experience before I do the medium sized layout I have been dreaming about for years. It will be in n-scale, thinking something like 3x6 or 3x8. I want to include a small yard, so I can get some experience with ops, stuff like making up trains and some loco service (refueling) etc.). It will probably be a small yard, maybe 2 or 3 tracks. I am not sure if it will be a stub yard or have a ladder at both ends. My question is how long do I want to make this yard from the ladder to the other end?
Thanks,
FT