Yes, that’s true the advice is 6-8 medium “encounters” which aren’t usually fights. But D&D is kind of bad at codifying costs of non-combat encounters. It doesn’t have progress clocks so trade-offs like “let’s go around the gorge instead of using Fly” aren’t mechanically represented very well. It has shit for social rules so it’s hard to do a social encounter that taxes resources. It can be done, of course, but the rules aren’t really helping much.
I think some people also confuse “per day” with “per session”. I’ve had multiple people tell me there’s no way they can do six combats in a three hour session, and I’m like what are you even talking about. One in-game day can go many sessions. Some people even give their players a long rest at the start of the session automatically!
Yup, it’s so hard to make resource expending non-combat encounters without effectively sidelining some of the party members. If you build an encounter that effectively requires spell slot expenditure, the martials are basically relegated to an audience position. And if you build an encounter where spell slot use isn’t absolutely necessary, the party will try every imaginable way of conquering it without using up resources first, defeating the whole point of forcing resource expenditure.
I guess one key part of this issue is that generally speaking, caster resources (slots) have universal uses in combat, exploration and social interactions, whereas martial resources only ever have combat applications. This, in presence of resource expending non-combat encounters, kind of creates a situation where your choice of caster or martial decides whether you want to participate in the game the entire time or just half of it.
