I think it really just depends on the baby. I know thats probably not what you want to hear

My Aunty saud her 2 kids fed every 4 hours much longer than 6 months, and they did not sleep through until 24 months and 19 months.

Other than during teething/illness, Milo has slept through minimum of 5 hours at night since he was about a week old, and by 8 weeks was sleeping 8 hours.

He now averages 10-11 hours a night. Sometimes I have to go in and comfort him, but not get him up etc, and sometimes when he is crying he's still asleep.

Are you exclusively b/f? Would you consider giving her water at that feed, if you were certain it was not food she was after?

Or just trying to resettle her without a feed - this is what I did when Milo dropped the middle of the night feed.