Is It Wrong to Try to Pick Up Girls in a Dungeon?

[Buffalobiian]

If I have a vision where I turn left at an intersection and a piano falls on me, and then I am for some reason incapable of turning right instead

You can turn right.
But a piano falls on you tomorrow. Or the day after. Or you identified the wrong intersection and you turned left at an intersection later on in the day and the piano fell on you then.

Did you change timelines by turning right at 10am when you first encountered an intersection post-vision? Or was your timeline always going to be that a piano fell onto you tomorrow and turning left or right on the first day didn't matter? The problem with these "what if" visions is that when it happens you think "That was foretold", but when it doesn't happen immediately you can't tell if it's avoided, or just yet to happen.

That's why there are always doomsday prophecies. Did they just not happen, or is doomsday just yet to come?

You write foresights in the manner by having the foresight be snippets of vision, and not a 2 minute video of continuous experience. This way, what you see is indeed factual and inevitable, but the context and circumstances are vague enough to have modifiable variables.

I know both styles of foresight occur in fiction, but the only one that makes any real sense is the one where the future never changes (regardless of whether the MC has foresight, or whether they can travel back in time [which in essence gave them foresight via experience]).

The way "What If" foresights could work is if the MC is able to see both paths and makes a decision based on that. Seeing a flash of one future only doesn't help.