Without wanting to piss on the PP's chips, I'd say quite a lot of babies, BF or FF seem to sleep through before 4 months and then when the 4 month regression hits it's back to several wake ups a night
At least both of my two have done this.
After that - if you BF mostly on demand and don't put any conscious effort into trying to get them to sleep independently the vast majority of babies will continue to wake in the night throughout the first year and it will tend to go back and forth without much actual improvement. It's normal and doesn't mean you are doing something wrong. Co-sleeping is a good way to deal with it if you'd rather wait for it to sort itself out. Just be sensible about it which includes not getting complacent about things like alcohol, bedding, and your own clothing having long ties or cords.
If you formula feed, or breastfeed in a bottle-like pattern (have set feeds, even if they are not at specific times, don't feed for comfort or boredom in between) or feed in a set routine, many babies will start naturally sleeping longer and longer chunks.
Likewise, if you do want to do something about sleep and you follow the kinds of tips you get in various sleep books, on websites etc, most babies will respond well to this (that's why most of the advice is broadly the same, the details many insist are the key are really unimportant) and will start lengthening their sleep chunks. There's "sleep training" advice with and without the whole controlled crying thing, so you can choose something which feels right for you. The common theme is routine so that a baby knows what to expect and feels comforted by familiarity, making change incrementally so that a baby feels safe and secure, and differentation so making day clearly opposite from night, plus making sure the period immediately before night is soothing and calming. You can do this in addition to feeding mostly on demand if you're consistent with feed-sleep associations for both night and day sleep, so it's not the case that breastfeeding on demand automatically = broken sleep.
But there are still some formula fed babies, routine parented babies, and a small amount of sleep trained babies who will consistently stick to the disrupted sleep patterns of the first year common in breastfed on demand infants. Sometimes it just happens that way, again, it's not a sign that something is wrong. This is physiologically normal infant sleep. If you get one that sleeps better than normal in response to the kinds of interventions mentioned, it's partly down to luck.
All babies (children) eventually get to a point where they don't need you at night, even if their need for night time parenting is so strong they resist all efforts at changing this.