Originally Posted by BogeyNoMore
^ Agreed - the reduction in effort, due to the additional power gained through stepping into the shot, can definitely result in better accuracy. But why is the additional power required in the first place? Because you're too far from the target to reach it very comfortably from a standstill. At this point it becomes a bit of a circular argument.
How does a run-up lead to increased accuracy? Because it allows you to generate the power needed to get the disc the desired distance with less effort. With less effort comes increased accuracy.
Inside the circle (where accuracy is paramount) no one runs up. The farther one is from the target, the more likely it they'll use a run-up, or at least a couple of steps.
This is definitely true, but there's one thing I haven't seen anyone say yet. The best analogy I can think of is juggling (random, I know). In juggling, you can start a juggling pattern (cold start), or go from a base pattern into a more complex pattern (hot start). The hot start gets your muscles moving and "in the groove". I think of a standstill drive as a cold start and a runup drive as a hot start. The runup helps me get into the motion of the drive, rather than just starting the throw from nothing. That can increase power and accuracy.
However, I've seen some people that could bomb from a standstill. And learning a good standstill throw will help improve your form overall.