Not quite. I’m saying that the prep for this six encounter dungeon multiplied by the number of locations that the dm provides for the players to explore - a minimum of three at the very least, up to dozens or even hundreds according to some- makes it prohibitively time consuming.
Again, that's what you
say, but that's really not true.
You don't have the time to do it. Perhaps you aren't using the right methods.
Let's take your Simple Dungeon of Six Encounters. OK, what's the dungeon? A home for goblins, maybe? We'll say this is a typical D&D world where adventurers routinely perform home invasions on goblins. Well, you only need a couple of statblocks, all of which are handily in the MM, with others online if you feel that you want to expand on those. Maybe you can go fancy and bring in some wargs or other "pets." I have vague recollections of some sort of sentient, talking, goblin-snake-ferret thing from an old monster book (maybe a Pathfinder bestiary) that I thought was cool when I read it, but that's easy enough to take something else, like a giant ferret and reskin it (I don't need to find the original statblock; my mental image is enough for me to go on). Maybe, if you really want to, add some other creatures that are sharing this lair with the goblins, like maybe strangling roots that have learned to not harass the goblins.
OK, so what's in this lair? Shrine, kitchen/larger, meeting room/dining hall, chief's room, bunk rooms (2), storage/loot room. Six places for encounters. You can even add a few more: a warg stable, the hallways, a hidden back room for goblins to go when they want some "alone time," a secret treasure room, a goblin tinkerer's room.
Draw some squiggles for the lair or use a random dungeon generator. This is the first time a random generator may come in handy.
Distribute the stat blocks as necessary. Determine some treasure. Here's the second time a generator may come in handy.
Decide if you want to put anything in the dungeon that leads to different areas of your campaign setting, that furthers a PC's plots or goals, or that hints at things to come.
If your PCs are the "kill them all and loot the bodies" type, you're done.
If they're the "lets talk to the goblins" type, you probably already have the reason the PCs are going to be doing that home invasion. Just come up with a few different motivations and personalities so they're people and not just cookie cutters of each other. A sentence or two is enough.
So that'll take, what, a half hour, an hour to complete?
Maybe two hours, if you decide to seriously personalize every goblin or every part of their lair. And depending on how long you have to play and what your PCs are like, this could be good for
many sessions.
Or to put it another way. Apparently DnD is fantastic at sandbox play if I choose to incorporate dozens if not hundreds of pages of material written by someone else. Doing it on my own is too much work according to virtually everyone in this thread.
I'm pretty certain you're the only one who's said that (that
we've said that you
have to have these resources). Pre-made encounters are a good resource for people who don't have the time or interest in making their own, but they certainly aren't required.
I'm writing up my encounters all by my lonesome. The most time-consuming aspect so far has been me trying to figure out if I want mimics and where I want them to be.
The encounters I'm prepping are for areas the players said they wanted to go into. If they decide at the last minute they don't want to, that's fine. I had fun prepping them and I can use them elsewhere or figure out what happened since the PCs didn't do anything about them. If the PCs don't encounter the people testing the monster-making spell, then they'll simply see newspapers talking about the mass destruction caused by the monsters. Last time I ran, a bunch of the game got derailed because one of the PCs decided she needed an apartment, so she and some other PCs went to go get her one. I didn't actually need to prep anything there. We were playing D&D (well, Level Up, which is D&D+) as complete improv.
So in reality, the only thing that's "hard" or "time-consuming" is the statblocks and things like spells and (in LU) maneuvers, and all of those things are in books. Unless you count "using the game's actual published material" as part of those "hundreds of pages written by someone else," in which case for shame, what are you doing playing a game someone else wrote?