Hriston
Dungeon Master of Middle-earth (He/him)
So the administrative concept of a round limits the story. That is what people are saying is a bad result. How would you like it if a movie character stopped for no story based reason in the middle of a chase?
This isn't what I'm advocating, though. You don't seem to get that in the fiction there is no break between one round and the next. The story doesn't include a moment where PC B is stopping at the edge of the chasm. The story I'm imagining is that B runs up to the edge and leaps across, which I think is the same story you imagine. So our difference isn't in the resulting story, but rather it's in how we choose to adjudicate the game at the table, specifically how we set the timing of the ending of one turn and the beginning of the next one.
...which puts him arbitrarily 10 feet back of where he would be had the administrative concept of a round not limited his movement.
I think this is what the issue seems to be about, despite the protestations of "story first". You feel the player is owed that 10 feet of movement in this round and is entitled to extract every last bit of movement from the system possible. I feel the game plays better when movement is divided into resolvable chunks. The player's character will get to cross that 10 feet in the next round when it can be resolved. Movement is only limited per turn. It isn't a finite resource. Feet are everywhere.

It is no hard at all. I've been using it for a long time. Your approach is simpler, but constrains the story under administrative abstract non-story limitations.
Again, there's no change in the story, just whether we get to that part of the story in this round or in the next round.
Great. Then why can't he move further in the round? He still has 2/3 of the round left. If the mechanics don't fit, you must acquit.
Because the round isn't primarily a measure of time. It's a measure of action (and movement). You can only do so much on your turn.
Run it how you want - each DM can decide what makes sense to them. Story first DMs will do something like what I do, but DMs that favor maximum simplicity and do not see a problem with arbitrary administrative features constraining the story will do something more like you.
I don't understand how you actually think the story is constrained, so it seems like a false argument to me. All we're talking about is in which round does a certain part of the story take place.