Page 509 — Chaperone Duty
There is one major exception clause to Never Split The Party, and that's when the party splits but is still "generally in town." Friendly territory, low chance of danger, and each group no more than a number of minutes away from each other should the need to regroup arise. It facilitates smaller, more manageable NPC interactions as the players run errands in several places at once, which makes it preferable to having the whole group of players talking to one NPC at a time.
Never Split The Party is far more strict doctrine in hostile territory, or — heaven forbid — the party try to go off on separate adventures altogether, going in different directions in the world. That's when someone has to bring the hammer down… usually.
Transcript:DM: Zecora leads the kids into a forested area close to the town – not the Everfree Forest, but dense enough to look spooky in the moonlight.
Twilight Sparkle: So, uh, is anyone going to back me up on this?
Pinkie Pie: I’m here! I’m in the kids’ group!
DM: Mayor Mare is also present.
Twilight Sparkle: Alright, that’s good. Anyone else? Applejack?
Applejack: What are my earnings so far?
DM: It’s… The night’s still young.
Applejack: Yeah, I’d better stick to my stall, for now.
Twilight Sparkle: Rainbow Dash?
Rainbow Dash: Hmm, lemme think. Legend? Orrrrr pranking.
Twilight Sparkle: Forget I asked. And with Rarity and Fluttershy out, that means it’s up to me, Pinkie, and the irresponsible mayor to watch over these kids.
Rarity: Actually… I think I’ll be around soon.
Twilight Sparkle: I… beg your pardon?
DM: Zecora looks ready to begin…