Watch the Picking Considerations 2 online guitar lesson by Bruce Arnold from Guitar Physiology Survival Guide
Picking too wide is also a common problem with students. Again, this will slow you down and affect your accuracy. You need a smaller, more controlled movement without tension, but this is exactly where an overzealous musician tends to use tension instead of relaxed movement to limit the motion of the pick; not a good fix for the problem as mentioned earlier.
Picking should be generated from your forearm as we will discuss later. I will give some suggested ways of limiting the pick motion at that time.