I am reading a number of ideas that go toward doing efficient prep work on stock for anything, but I am not seeing the words that talk just about lengths of stock for a final type of prep. My thought is you should cut all stock so it is never more that 4 or 5"longer than final needed part for whatever you're making. In doing this a lot of the many different forces you will see on "longer" stock, just simply go away. If you take a 14' long board and cut it to 37" you will see 2 entirely different results on your stock, and every time doing them at that smaller length will be much more efficient, and getting 4 square will happen a lot faster. Just adding that in, because as much talk and discussion about roller stands needs this added in. IOW prepping really long stock, with thoughts that the long stuff will just need to be cut down to shorter lengths.
Well in theory it sounds like less work. I've found in practice it really is much more work. You can get parts ready close to their needed lengths a lot easier, and faster than trying to dress down stock in a long piece, and then cutting it to needed lengths. This is true because the longer the piece of stock, the more twists, curves, and bows you will have to deal with, so that trying to prep extra long pieces, will actually have you whittling down the stock, more than you want it to be.
Now if you "are" building long boats, and need extra long stock, well then you just have to roll with it, and do the best you can, but seriously, if ALL projects are factored in, then prepping 12' long stock is making more work for yourself.