targets that no two of which can be more than 30 ft. apart

[Bandw2]

does this have to persist? or after you cast the spell is the effect fine for the duration.

basically if someone walks more than 30 feet away, does the effect end?

[dragonhunterq]

Without knowing the specific spell - which might have wording that changes the general rule - I understand that once a spell is cast you no longer need to target the subjects, so they are still under the effects of the spell if they wander off.

[Jeraa]

Bandw2 wrote:

does this have to persist? or after you cast the spell is the effect fine for the duration.

basically if someone walks more than 30 feet away, does the effect end?

The effect only ends if it specifically says it does.