Presumably the reasons for the initial attack still exist
Then… they failed? You’re saying that if they win, they fail. Or at least, they can’t win hard enough to actually get what they want.
You’re also assuming Russia wants territory. If Russia wanted, say, Ukraine not being admitted to NATO, and they can get a peace that ensures that, then there isn’t a reason for them to invade again. Or if Russia wanted UKR to stop shelling the eastern regions, then annexing just them might stop that, in which case, they don’t have any reason to invade again.
No no. It was a great strategy. Germany went to war. It was just that Germany also went to war with us, which wasn’t what we wanted.