Can speed practice alone help long distance endurance?

Thanks again, everyone. To combine the opinions, perhaps for long distance and open water, the #1 factor is, like in any other swimming, technique. But beside that, if I practice fast swimming with no or very short rests (less than 30 seconds?), I will be able to swim short distance fast (which consumes more energy than in slower pace). Then, when I swim long distance, since I'll slow down, the energy needed to swim 50m in fast pace will enable me to swim, say, 200m in slow-and-steady pace. I admit this is partly out of my unwillingness to do long, boring long distance in a short-course pool, which conflicts my wish to swim long distance in open water some day :) I'm still open to all input--experiences will be more helpful than theories, so if anyone out there can relate to their actually experience it'll be great. :)

Thanks again, everyone. To combine the opinions, perhaps for long distance and open water, the #1 factor is, like in any other swimming, technique. But beside that, if I practice fast swimming with no or very short rests (less than 30 seconds?), I will be able to swim short distance fast (which consumes more energy than in slower pace). Then, when I swim long distance, since I'll slow down, the energy needed to swim 50m in fast pace will enable me to swim, say, 200m in slow-and-steady pace. I admit this is partly out of my unwillingness to do long, boring long distance in a short-course pool, which conflicts my wish to swim long distance in open water some day :) I'm still open to all input--experiences will be more helpful than theories, so if anyone out there can relate to their actually experience it'll be great. :)