Wait what? Let's step back for a minute here. If you're designing the encounters for your world... how??
For the campaign, which includes the world, among other creative considerations. So, for an obvious instance, if the world doesn't have elves, you wouldn't have an encounter with elves. If an area is established as overrun with griffons and bulletes, it's very unlikely you'd have an encounter with horse-riding nomads (because both those monsters love horseflesh).
That's obvious, but softer considerations, like the theme of the campaign or the feel of an area of it or the 'needs of the story' or whatnot can also factor into how difficult and how many encounters you might want to throw down in a given period of time - be it a day or months or an hour (there's plenty of time for multiple encounters in a single hour, in a practical sense).
There's a certain amount of restriction "balance" requires otherwise everything and anything in the game in every and any combination would be "balanced"
There's restriction that 'balance' (which is strictly optional) in 5e requires, yes. 'Balanced' can still mean 'this is it, we're all going to die,' in the face of a string of deadly encounters, but you'll all die without one of you showing the others up, FWIW.
(are there any examples of a game that operates like this??)
Yes. Any game that doesn't use attrition across encounters as a source of challenge would be indifferent to the number and timing of encounters. And, any system that doesn't differentiate classes (well, groups of classes) by giving them different supply, timing & power of limited-use resources, would be indifferent to the ratio of encounters to resource-recovery opportunities in terms of class balance (not in terms of encounter difficulty, though) - including classless systems, which, outside of D&D and it's immitators, are probably the norm for RPGs, not that anything as niche and unpopular as TTRPGs has a 'norm.'
So, really, yes, quite a few, just none of them D&D (not even 4e, the 'not D&D D&D,' though it came closest)... well, "D&D" Gamma World was that way, but the 'D&D' part was un-called-for, IMHO.
For one instance (a not at all balanced game in many other ways) I ran Mage: the Ascension for quite a while. If you had a Monk and a Wizard in D&D, their different resource-recovery mixes would make tuning the encounter/short-rest/day ratios to keep them 'balanced' advisable. If you had an Akashic Brother and an Hermetic (basically the same concepts/archetypes), in M:tA, there'd be plenty of other things imbalancing them relative to eachother, but how many different times they threw down with agents of the Technocracy that day wouldn't be one of them.
and there's also a certain amount of responsibility you have to take for utilizing the tools correctly or incorrectly to achieve the goals you want...
Yep, I believe I said something like that - of course 'utilizing the tools correctly' can include tossing or altering them, 'cause they're just a starting point.
What exactly is this campaign world where these rules won't work and why?
Really, they don't work in any world. Not until a DM steps up and takes events in hand to make them work.
Well you have as much right to conjecture as the next man. Personally before I go down the path of doubting something I'd give it a chance...
One of the perks of 5e is that it is close enough to the classic game that we can apply our hard-won DMing skills of decades past to it. 5e's Elephant is much like the Mastodons of those days, none of this is really a mystery.
Just for one instance of a factor that confounds the 'solution' of 3-4 double-strength encounters:
When you dial up difficulty in D&D, as you'd have to do to cram an encounter budget and challenge of a whole day into 3 encounters, the PCs are in more and more obvious & immediate danger, and they respond by blowing their most potent resources - their biggest slots, powering their best spell for the circumstance, for instance. That's when the classes with those resources get their spotlight time. In the 6-8 medium-hard guideline, they'll more likely shine in the hard encounters, while others will shine in the medium ones - and that's an issue of it's own, too, but no need to go there right now. In the 3-deadly alternative, the volume is turned all the way up, all the time. Similarly, much as I like the idea of multiplying short-rest abilities to bring them into line with long-rest abilities in a single-encounter day, the daily abilities are still typically more potent, individually (and in the case of spell, more versatile, as well, though, again, another topic...).
I don't think "failing" means what you think it means.
It means what I meant it to mean in the context as I meant to use it. ;P
Seriously, though, yeah, I can be harsh with systems. We could spin it as the system 'presents you with an opportunity to exercise DM Empowerment to better your campaign's play experience' rather than 'fails' just because
If I'm using the guidelines and my game is running the way i want to... how can it be failing??
You could be missing out on running a better game if you were not constrained by those guidelines...
:shrug:
The qualities of a system don't change just because opinions about them or experiences of them are necessarily subjective.
