I had an amazing flub last week at Curse of Strahd. I a few different locations along their travel plan only to realize in game that all of those locations won't let them in until they finished an area I hadn't prepared yet. Egg on my face.

Welcome! To the wondrous land of Railroading!

Doesn't have to be railroading for this sort of thing to occur. You can't out-plan effectively infinite options, and it's important to set a baseline of expectations not only of the DM but also of the players. Shockingly, some players don't understand the basic "find a reason for your character to travel with the others" concept unless it's spelled out to them. There's also some players that will intentionally play as though they're allergic to main plot threads, which can be fine if that's established going in but a pain in the ass if there was an understanding that the DM might be able to prepare shit in advance and not always instantaneously adlib. Like don't agree to Descent to Avernus if you don't have any intention of going to Avernus. *** Sorry, I get you were probably joking, but I've also been in some groups that just didn't work out because players weren't straightforward about what they were looking for.

Yeah, I don't subscribe to the old ways of players vs. DM. In fact most of the people I play with see it as a kind of collaborative narration that has game elements. In fact, if someone can have an epic death, they would pursue it. So yes, most of them are fully onboard with following the story, though some gentle nudges might be needed

My locations are like vague outlines until people express interest until going there. Then the details emerge.

I feel like there's some sort of corollary to Murphy's Law, where players will think of the one thing I didn't include in my session prep. Gotta break into the cult compound? "Let's use the hot air balloon we saw six sessions ago" I love it when players do stuff like that, but it's a pain in the butt. It taught me to prepare less.

Woah, woah, woah... Its called "sandboxing" now.

My experience with Sandboxing was... it is a lot, a lot of work, somehow it felt like running a theme park, and I needed to create a town of NPCs, all with interconnected stories that players can catch-up and follow, with "rides" or rather events that happen to spice up the play, instead of just going around playing 20 questions. What happens though, is that if you tell everyone that it will be a sandbox, they'll go ahead and be very creative, to a point they'll throw a spanner in the works, and you'll see those carefully created NPCs with rich backgrounds, connections and quests die at the hands of mad murder hobos. (Not always though, experienced players understand this is a theme park).

prep is for chumps. real players say fuck it we ball.