Personally, I ignore CR and don't worry about PC vs monster balance--the monsters and NPCs exist in my campaign world independently of the PCs. It's mostly up to the PCs in my campaigns to decide what to try to engage (at least until they provoke an NPC into hunting the party), and that includes trying to make sure that they're properly prepared if they're going to try to punch above their weight class.Frankly I am amazed at how low most of the votes are. When I voted 3 I was sort-of low-balling it due to the travel and town adventuring days where long rests aren't needed in the absolute sense of resource recovery.
I know many people who use fewer encounters ramp up the difficulty to routinely hard or even deadly, but that sort of thinking has never really set well with me.
The thing I am doing right now is basing encounters on the game-world concept of creature rarity based on CR primarily.
In short, each encounter has a base of tier 1. A d6 roll of 6 ramps it up to tier 2, another 6 to tier 3, and a final 6 to tier 4. I don't care what tier the PCs are... If they encounter something below their tier it will be easier, and something above their tier they might have to avoid or flee from, etc.
I live in rural upstate NY, so I explain it like this:
If I see a squirrel, that is tier 1 (basic creature seen/encountered all the time)
If I see a deer, that is tier 2 (common enough that I seem them often, but not all the time)
If I see a black bear, that is tier 3 (something I see once in a great while, but I know they are out there... so I am always cautious while hiking, etc.)
If I see a rattlesnake, that is tier 4 (I know they are around here, but I have only ever seen one in my life)
Now, I try in use sufficient numbers, terrain, etc. to make the encounters at least minimally challenging when the PCs are higher level and things from tier 1 would not otherwise be much of a threat, but when you consider tier 4 includes CR 4 creatures, it isn't too hard to manage.
It does mean, however, that tier 4 PCs will not always be encountering tier 3 and 4 creatures (just to make it a challenge) like most games... they will often encounter tiers 1 and 2 when they get there.
In my current campaign the PCs have mostly opted to backburner adventuring opportunities that would lead to dungeons (or dungeon analogues) with the potential for sequential combats, in favor of pursuing objectives they've deemed more urgent. Some of those objectives have been resolved without any combat--usually when the party was obviously more powerful than their opponents and could leverage that strength to achieve a non-violent resolution--and some of which have been resolved by the PCs hunting down and deliberately attacking the NPCs, either because eradication was their chosen objective or because the NPCs were too powerful to otherwise coerce. (The latter of which naturally leads to combat encounters far beyond what the DMG would classify as 'Deadly' if I was using CR.)
My answer is 1 under either formulation of the question.I agree, but you still have a number of people talking about only doing a couple encounters daily when it is a "meaningful portion of encounters". I personally don't count non-conflict encounters into the equation... no resources are used, you could have an infinite number of them in theory without issue.
And most of the spellcasting and other limited-use resource expenditure at my table is done out of combat, either in pursuit of non-combat objectives or when trying to set up a planned combat encounter to their own advantage.