Are unpaired stairs common?

[ShadowbirdRH]

I've only had two worlds that I've explored completely enough to find this, but in both of them, there's one more set of stairs than there are sinkholes, with the one unpaired stairs sending the player to the florid postern on the surface. Is this in every world, or more of a rare oddity?

[chirsg]

I have come across it a few times. I can't say for certain it's every world, but I have 2 active worlds that feature this.

[Creatorofswamps]

It happened quite recently

[DajeKotlyar]

Not a single time

[Nogard78]

You can fix it with command if you like(and can use console). 

But as for question, it happened to me once, but I presume it was because I was using a mod that change worldgen pretty signidicantly. 

[Evelo]

It occurs more frequently if you mod biomes. There are a fixed number of stairs in the caves but the surface has limitations on the locations of the cave enterances, typically 1 per biome or something like that. So if you change the surface dramatically without changing the cave (excluding ruins) biomes then you are likely to have more stairs than cave entrances.

I accepted this as the way it is going to be for me because of how much of the surface I remove.