One response then has been proposed by
@Maxperson, which is that the table is used only because the fiction contains the right conditions. That seems to mirror
@pemerton's careful and repeated explanation that the consequences of fail forward (such as a chef) can and ought to be prefigured in the fiction.
Yes. What I will do is something like the following.
The players decide to break into the wizard Alchaeus's tower. Alchaeus has two servants who live with him. His apprentice who also doubles as his personal servant, and his chef. While the players are discussing their plan to break in, I'll figure out the chances that one of those three will be awake around 2am, which is when the group will be getting to the tower.
As I mentioned upthread, the odds of someone 1) being awake during the middle of the night, 2) that person being in the kitchen where the rogue is picking the lock to get into the tower, and 3) happening to be there during the 1 round to few minutes it will take to pick the lock and open the door, are very low. Even though they are probably lower than this, I'd probably assign it a 5% chance that someone will be awake and if I roll a 1 on the d20, someone is.
If a 1 is rolled, I'll then figure out who is most likely to be awake and why. The most likely person to be awake would be Alchaeus himself, up late studying or working on a project of some sort. The second most likely would be the apprentice set to some task that is taking foreeeeeever and needs to be done before Alchaeus wakes up in the morning. The least likely would be the cook who probably has to wake up early to make breakfast for everyone and it needs to be done when the other awake and come downstairs. She would need her sleep during the night.
The roll on the impromptu table happens and wonder of wonders, it turns out to be the cook! Now, why is she awake? Having to go to the bathroom is most likely, followed by insomnia, followed by some obscure other reason. After assigning percentages to those three things, I'd roll to see which pops up.
If she is just going to the bathroom, she won't be in the kitchen and will likely be using her chamber pot upstairs somewhere. If it's insomnia, then there's a chance she will be lying awake in bed, sitting in her room doing something or other, or maybe go down to the kitchen for a snack. If it's an obscure reason I'd likely just try to think of some reason she couldn't sleep over it, like maybe a loved one recently passed and she can't sleep due to grief or maybe she has some sort of injury and pain is keeping her awake. Since there are a lot of obscure reasons it could be and I don't have time to come up with a bunch to put on a table, I'd just choose one if that result came up.
Also note that if Alchaeus or the apprentice had been rolled, there would be a few other things on their table, including obscure reasons. It wouldn't just be the one thing I mentioned above. Those are just the most likely reasons for them, but since I didn't roll them in this example, I didn't go any further with them.
At no point, though, would any of that be predicated on the outcome of the roll to pick the lock of the kitchen door.
Another response, also by
@Maxperson (and apologies if I'm misreading) is that tables may also be situation establishing (part of setting up the fiction). I need to reflect on how that stands in relation to the general worry.
Sure. A random encounter affects and establishes part of the fiction depending on what is encountered and where.
I also sometimes use Central Casting Dungeons to roll up a random dungeon, castle or whatever if I don't have a clear vision for it. It's a really good resource if you also make sure that the rolls don't come up with something that doesn't make sense.
Sometimes those random rolls fit together in such a way as to supply a vision for the rest of the dungeon. If a lot of rolls dealing with war and combat related things come up, perhaps it will inspire a vision of a ruined castle of a warlord or a ruined temple to a war god and then I'll be creative in that direction.
The point is that these tables are used to establish fictional situations. Those are also non-exhaustive examples of where tables can be used for that purpose.