In very large drum circles, it might mean that drummers who can follow the leader visually are spread out, so that the drummers by the ends have a close drummer to follow.
Ask. As simple as it sounds, choosing to just place yourself next to the drum circle leader might be disallowed.
As an outsider, do not presume it is okay to choose where you sit. For example, telling the drum circle leader, "I'm going to sit next to you".
Choosing to sit next to the lead drummer puts the drum circle leader in the uncomfortable position of needing to correct you and move you.
The group of musicians and drummers sitting at the core of the drum circle frequently collaborate with each other during the performance. In smaller venues it might be by low volume speaking; in larger more rambunctious venues it likely requires more volume. The group coordinates things like