So practically-speaking, for the short, the teams are split in half based on World Standings. The top half have a random draw for the final few groups, and the bottom half have a random draw for the earlier few groups.
If you are ranked #1 in the world standings, you may compete in the short in the second to last group rather than the last group based on the draw among the top half of the competitors, but you won't be going in the earliest group because the bottom half of the WS teams all skate first. Likewise, if you are ranked #8, you could be last to skate in the short. But if you are ranked #20, you will be up during the first half of the competition.