Long to short is usually incorporated when the speed aspect is there but endurance is needed, correct? And vice versa for short to long right?
It depends who you ask! The consensus here seems to be that if you’re deficient in speed but you have good endurance you should go long to short and vice versa. However the concensus at CF.com is that you should work to your strengths first.
It also depends on what your definition of long to short vs. short to long is, which also varies from place to place, person to person. I agree with cockysprinter re: long to short. I think you can get more than enough endurance work done on a both ends to the middle approach.