The following situations to me make tremendous sense:
Create a new measure when I am in Write mode and I enter more material than I have bars for: Good.
Create a new measure when I am in Write mode and I enter a key signature/meter change at the final barline: Logical, great.
Create a new measure when I am in Write mode and I enter additional bars in the Bar popover: Great!
Then there’s this one:
Create a new measure when I am in Engrave mode and I enter a System or Frame Break at the final barline: Why?
I have to imagine this is somehow intentional behavior, but who is using this feature in Engrave mode of all places? The last thing I think anyone would need is worrying about accidentally adding measures at the end of pieces when laying out parts.