Kids go through phases just like adults do, like when you start a new job you gradually acclimatise to your new surroundings, gain new skills, and develop relationships.
Kids do the same thing in so much as it’s gradual shifts from one phase to another.
Sleeping soundly shifts to waking three times a night, being calm and patient makes way for a high strung three year old.
There are no hard and fast “milestones” just like you every kid is different.
Let’s try and remember that.