When it says "next time, an extra chapter", does that mean we'll get both a regular chapter plus an extra one, or only the extra chapter?
If it's the later, then what does "extra" even mean? Off-topic? It's not like the manga has a clear direction anyway.
In editor speak "extra chapter" means "wait a bit before the author comes up with something new, so enjoy this idea I shelved months ago"
It also means the same as "taking a break", "doing research", "playing idolmaster"