When I was a kid new to RPGs in 1985, having discovered the Basic Set and then the Expert set, the only premade adventures we ever used were the Basic dungeon, Threshold and environs, and The Isle of Dread. These were sufficient to teach us how to make our own adventures. For the most part, all through the 80s, 90s and early 00s I never used published adventures. I bought and read some, including Dungeon Magazine and adventures for other games (I especially liked reading Champions of DC Heroes adventures) but I used them as inspiration or to steal stats from. I did dabble a little in trying to run the original Dragonlance adventures at some point, but it did not go very well.
Later, in the mid 00s, I started using published adventures more. I ran the 3E "adventure path" modules (Sunken Citadel, Forge of Fury, etc) and Red Hand of SDoom (still th best module WotC has ever published). It was not until the Paizo and Pathfinder era that I really started running pre-written adventures more often. More recently, using Fantasy grounds for most of my gaming, I now run adventures more often than creating my own.
But here is the thing: I really, really don't like running modules and I absolutely hate reading them (especially WotC and Paizo style modules). I still default to modules when learning a new system (Shadowdark, for example) just to get a sense of the design intent. But if I like the game and I "get it" I prefer strongly to just run the game.
Part of it is simply that I am an improv GM and I don't see the value in detailed adventure design even if I am writing it. A loose outline, a handle on the rules, and a list of names are really all I need. That is how I run games in person and at cons. I just find that more difficult on Fantasy grounds than it is in person, so I default to adventures. But, Monday I started a new adventure "my way" even using FG and it went great. Now, I am dreading running my Pathfinder2ER Abomination Vaults campaign tonight because I do not like the adventure as written.
Anyway, enough about me. How do you feel about published/pre-written adventures? Do you run them as is? Strip them for parts? Don't even consider them? When you run an adventure of your own design, do you "write it" before play? If you do use pre-written adventures, what kind of "prep" do you do with them?
I'm pretty much exactly like you - I started in 1985 (though I didn't DM until 1989).
I didn't even
read published modules or Dungeon or Dragon for inspiration. I used fantasy novels for inspiration on
story structure but I believed strongly that using any details was plagiarism. It annoyed me when some of my players tried adding stuff to our shared world that were from books or published adventures.
The first published adventure that I tried to run was Forge of Fury under the idea that I should give it a try to go with the "new" 3rd edition. (I had looked at Sunless Citadel and rejected it without trying). I
hated it. (I have since grown a slight fondness for it). I went back to running 100% my own made-up adventures until 2008 (though I think I might have tried White Plume Mountain and hated it, too.)
When 4e arrived, I changed my ways. Not because my attitude is all that different, but because I became a better businessman (I've owned my FLGS since 1993) and I decided that it was smart to make it at least LOOK like I think published adventures are worth buying! Since then, I have run
most adventures that have been published for both 4e and 5e. I honestly think that it's much much more work to run published adventures, but I put the work in so that my players can be involved in that "Shared Experience" with people across the globe and say that they've been to Chult and fought Acererak (or whatever).
That part I guess I like about it.
The way that I get the "Improv DM" that both you and I like out of my system is that I try not to be so attached to the module that it constrains me (or my players). So whenever people complain that "Horde of the Dragon Queen is too railroady" (or whatever) I think "So? Don't let it be."
My advice to people running published adventures is "Ignore it wherever it suits you to. You find something you don't like? Do it differently." Heck, I'd add "Read it the night before. And then don't use it at the table. If you can't remember something, it's probably not worth much. Make something else up instead".
I admit that advice is not for everyone, only a certain sort of DM.
In the end, my attitude has changed about published adventures - I now think that a lot of poorly reviewed adventures are much better than a lot of people say.
It's precisely BECAUSE my expectation is for them to be
terrible. Their flaws are
expected and therefore don't bother me. Because I don't like ANY adventure, I can enjoy ALL OF THEM. (Or nearly all).
To me, 5e has a very good track record for Adventures, though I don't like their layout. I mean, the 4e ones were often much worse, but at least they were laid out to be
run, unlike the 5e ones that are laid out to be
read.