I don't think that's true.
One group wants it to be hard to recover to 100% if you have 6 encounters
One group wants you to have 100% power every fight but only have 2 encounters..
That's not the read I'm getting. One group wants attrition of offensive power throughout the day*. You use a
fireball on those 8 orcs – great, that made
that encounter easy, but now you're down one
fireball. You need to carefully ration when and how you use your magic (because it's mostly spells that are affected by this). This also needs to be weighed against hp loss: if you
didn't blast those orcs out of existence, how much damage would they have done? And would that damage require more resources to heal than the
fireball cost? In this model, each encounter is mostly a foregone conclusion – the question is whether you're ahead or behind on expected resource use, not whether or not you'll win that fight. And later in the day,
that's when encounters become threatening for real, because you've used up your reserves.
The other group wants Maximum Effort, all the time. Much like you go into each boss encounter in World of Warcraft with full hp, full mana, and with all your cooldowns ready, they want the same for each encounter in the game. You probably have fewer resources immediately available, but you only need to worry about them for this one fight. There might be some healing surge-like mechanic that limits the number of encounters you can endure, but until you hit that limit you're golden. In this model, each encounter is threatening in and of itself and you need to use your resources to defeat it. But that's fine, you'll get them back.
(A sub-group of this is the Draw Steel type, where you go into each encounter with few resources but build them up
within the encounter. Maybe you'll have to make do with
fire bolt for a round or two before you have enough juice to cast a
fireball.)
This does not have to do with how many encounters you can handle in a day. It's about how much juice you have for each encounter. The first group has a big juice tank but has to make that tank last all day. The other maybe has more of a juice glass, but can get free refills at the counter once you're out of combat. The problem with 5e is that it's designed for the first type, but many people play it as if it's the second type and then need to rest all the time which breaks both verisimilitude (because of the 5-minute adventuring day) and the game.
* or week or whatever time unit you want to have for recovery.