abirdcall
(she/her)
I find things like encounters-per-day and XP budgets and CR to be, at best, useful guidelines and usually not even that. I prefer a game that is organic and improvisational in nature, in which exploration and interaction drive the pace and the story is an emergent quality. I am not saying this is the right way to play, but it is what happens at my table. I have developed it even for cons, where I run an open world, ongoing game over the course of 4 or 6 slots. I have never wanted for bottoms to warm seats. I think the need for structure is overstated by many. I mostly blame Paizo. They did not invent the structured campaign but they perfected it and the explosion of "adventure paths" steals what I think is the best quality of tabletop RPGs: the crazypants uncertainty about what can happen next.
I think you are selling yourself short. There is still a structure to your open gaming. An independent viewer would still be watching a story unfold. There would still be levels of pacing.
I agree that predetermining the story isn't great for D&D. That is not what this is about.
It also goes beyond just the encounters. The DM can help to set the pace in other ways such as enthusiasm.
Maybe that should be another topic.