Understanding positioning and distribution of players on the field is an important skill, but also somewhat of an innate ability. How this skill manifests itself is sometimes subtle and other times overt. It can show up in the guy who always seems to be making the good cut to keep the offensive flow going or in the physically ungifted player who consistently finds themselves alone in the endzone. It can be the thrower who is able to find targets on the goal line or the defender who gets a lot of poach blocks. It can be the popper/wing in zone offense who is always touching the disc or the defensive wing whose side the disc never advances on. All these traits come from someone understanding the space around them and where the players on the field are moving.
I was watching a Division I basketball practice once when a player made a mistake and the coach, rather than ripping into him, asked the player what he saw when he made that decision. By understanding the information that the player was working with, he was better able to instruct the player. This questioning is something that every player should endure, and at least ask themselves, whenever a mistake is made. Did I recognize that poach in the lane? Did I understand the balance of players on the field? Where was the open space for me to cut to? Did I need to protect against my receiver going deep when he was already 50 yards away from the disc? Of course, these questions only deal with the perceived information, rather than what may have actually happened, but it is a good starting place.
Developing field vision, or field sense, is a difficult thing, and requires acute awareness of the other 13 players on the field, even while being involved in the play. One thing that a thrower can do in a practice environment is to throw the disc to the place where he sees the space, even if there is nobody cutting there. By making this throw, it becomes obvious where he is looking, and where he sees the space on the field. Cutters can also draw attention by yelling at the thrower to alert him to where he should be looking. Both these examples deal with one-to-one or one-to-few player interactions. Developing this in a one-to-many or many-to-many fashion is more difficult. There are some drills where a player turns to see a selection of cutters, some which are marked, and others which are unmarked, and has to recognize which players are open. This drill deals more with recognition of cutters, rather than using space, but hopefully through this recognition, a deeper level of identifying open cutters can be achieved. Another situation may be where players close their eyes and then open them as the disc becomes active; they have to quickly get a sense of the balance of players on the field and where they should be moving, recognizing who should be cutting, or what lanes need to be plugged before resuming the offensive/defensive plan.