In my many years of running, there is one aspect that is so greatly overrated and so burned in runners' minds that they can't see it's obvious shortcomings. The necessity for a long run, especially a lsd.
Sure, for a marathon, there needs to be a long run. But for races of 5k to 10k, a long run is useless. Somehow, these runners think that by running long and slow it will magically transform to faster times. Nonsense! They are better off trading that day for another day of speedwork. Adding a longrun is only padding the mileage. If a runner is already doing a sufficient amount of mileage, adding a long run will do nothing to help the runner's times. It won't magically translate to faster times. Even if a runner needs more mileage, the long run only adds more mileage. There's no magic in it. Replacing it with speedwork will result in faster times. My times improved dramatically when I dropped my lsd and replaced it with speedwork.
The long run is the most overrated aspect of training that has ever been concocted.