I think if it isn't, the DM is unnecessarily risking their credibility. Certainly between the OP and what
@jmartkdr2 said, I think it more or less must be, yes.
By what criteria are they risking their credibility? I mean, I get what you're saying, and I think I would likely view things similarly....but my personal preference aside, I don't think that this kind of stuff is counter to what's offered in the books.
So, is having Strahd prepare while the PCs are resting negating the long rest? If they've done intelligence-gathering, is his ability to prepare previously established?
It depends on what's been established. Changing the facts out from under the players' feet is kinda dirty pool. Giving Strahd resources the players would have noticed (but didn't) seems like that.
That seems like a reasonable way to run the adventure. Seems as though by not undoing their achievements you were honoring/rewarding player skill, though, whether it was a worry for you or not.
I think the story that was so important to you was the result of how your table had played the game. If you never undid any of their achievements, you were honoring skilled play, as well as the story. My point is that conflict between them isn't necessary--and you managed it even within the confines of a long, published adventure.
Sure, I honestly don't think that honoring skilled play and trying for the most exciting version of events here happen to be at odds. I think we've all acknowledged that these two play priorities aren't always at odds, just that they may be at times.
My recounting of this scenario (prompted by the mention of Strahd) was largely about the fact that in my mind, no matter what they did, this was going to be a difficult encounter. There was a dial, and I was willing and able to adjust it, and do so invisibly.
For example, they had the Sunsword. So Strahd had minions on hand not susceptible to the Sunsword's power, and they swarmed the fighter who wielded it, and tried to take it away from him. I did this to make the encounter more difficult. However, would I have added those minions if the players had not managed to find the Sunsword? Probably not.
Is that kind of encounter design consideration contradictory to anything suggested by the books?
Or, if the game is a mix of the 2 cited play priorities in the DMG page 34 (the ones I outlined in the lead post and just spoke of above) and the GM infers/extrapolates in their "find the fun...find the memorable story" permutation that a Long Rest recharge will wreck the climax and damage the Immersive Storytelling priority ("Strahd's soft! That ending sucked! What an anticlimax! No way he should go down like such a chump!") of pg 34 (where, again, the GM is encouraged to change or ignore the rules for the play priority's needs...right there in the text)...why should that GM feel badly making that inferrence/extrapolation and changing/ignoring the rules in order to make Strahd not be a chump...in order to protect against anticlimax.
I don't see how 5e has a monolithic voice on this at all and the designers absolutely didn't intend for it to.
I don't think it does. I think many folks are answering out of a reflex to not undo player achievement. I think that was a large part of my initial answer. But now that the conversation has gone on and I've given it some thought....I think that was a kind of knee-jerk response.
I think honoring their successes is important. But is it more important than having a fun and immersive experience? I don't know.
If you looked at threads about running Curse of Strahd, you'll see lots of complaints that he's a pushover. Especially if the PCs are armed with some of the artifacts that they set out to use to beat him. I know for a fact in those threads, most of the advice was "if you really want him to be challenging, you need to do X" more so than "if that's the way things go, then you should honor it", although those sentiments were present, as well.
I know that any part I took in those discussions was to offer suggestions on how to play Strahd more effectively. Does this qualify as a focus on "do what's most exciting"?
A lot of this does depend on details -
- I'm assuming the players were able to establish a scenario where they could reasonably expect to get a whole rest in. They've scouted, pacified, and secured the area to remove the risk of wandering monsters. They've taken into account the fact that the enemy might be aware of them coming and making their own moves. In other words, setting up a lac of interruption is part of "earning" the long rest. If it can be interrupted without violating the established fiction, than that happening isn't violating skilled play or the story.
- one effect of taking a long rest in such a campaign would be "the bad guy also gets an extra 8 hours to prepare." It's a cost/risk of the long rest. This gives the dm a lot of room to adjust the final encounter to dial up the difficulty. A well-written adventure would include tips on how to do this, such as items like a set of braziers of commanding fire elementals which could give him some extra muscle, but only if you give him enough time to get it set up. (Again, ideally, the players should have had a chance to find out about these and factor them in to risk calculations.)
But arguing the example aside - at some point it will come down to "following the rules" or "following the adventure plan" or "doing what seems like it will be the most exciting." It seems that here at least, there's a 4-to-1 preference for the first one.
What rules would be broken by "doing what sees like it will be most exciting"? I mean, if we take the rules in their entirety, the DM can basically override any of them.....so this doesn't seem to be about rules so much as about an individual group's preferences and play priorities.