I've been doing some thinking about player choice/agency. Part of that is this Twitter post that I found as a meme that really encapsulates what a lot of people (myself included) would likely take thousands of words to express.
Another thought, somewhat related to the meme, is that combat is really all of this writ small. Especially in a system where there are a lot of rules and options centered on combat. In a combat scene, or even a combat round, these three criteria constantly come up. So combat is an area where players (seemingly) have constant agency.
But I think that stands in contrast to a lot of RPG plots/modules, which are typically very linear, if not railroads.
One thing that I'm surprised I haven't discussed here is the difference between "if" and "how" in RPG plot construction. When preparing a one-shot, as I have often been doing, you do wind up doing more railroading to make sure that the session reaches a satisfying conclusion in the time allotted. A lot of RPG mechanics are designed around the question of "if." For example, we often roll dice to determine "if" the character succeeds at an action.
But if you're writing a linear scenario, whether for a one-shot or for your corporate overlords, "ifs" create roadblocks, branching paths, and other extra work, which should be avoided whenever possible. The better option is "how." Rather than asking "if" something happens that the adventure needs in order to proceed, ask your players "how" they make it through the challenge.
This can be very freeform. I remember the Cthulhu-Trek scenarios that I played at DunDraCon all those years back were very linearly structured, but exactly how the group addressed the challenges was very much decided by the group. I remember looking back on those sessions and thinking that I had been tricked, because "if" was never the actual question. It was always "how."
Looking at RPG combat, I see a lot of the same thing. No matter how much it's framed as an "if" situation (Can Our Heroes win this battle?), all of the balancing mechanics and "Get Out Of Jail Free" cards and GMs just pulling their punches, the overriding question of a combat scene is actually "how" (What combination of powers, spells and dice results are going to let Our Heroes win?).
Circling back to what I hope was my original point, combat offers players agency within the confines of its mechanical structure. In a railroady adventure, this limited agency acts to paper over the lack of agency regarding the overarching plot. Especially now that it's part of my adventure writing toolkit, it becomes something that I can't unsee when I read a published adventure.



