as a regular long run runner and coder, I totally agree with you. For training, not only building base is important, if you wanna achieve a good pace during marathon, running fast like a blast is part of it. More detailed, we basically have 4 phases for training. 1)acclimatizing phase, 2)building-up phase, 3)overall preparation phase, and 4)special preparation phase. Hacktons are more like phase 4, not so accurate analogy,but the spirit is the same. Digging deep, changing the routine, a big improvement is coming.