Really depends on your dataset size, right? You give 1 billion as an example, that is 8GB of RAM in a single data structure just in overhead if you have a point

Really depends on your dataset size, right? You give 1 billion as an example, that is 8GB of RAM in a single data structure just in overhead if you have a pointer for each tree leaf. This data structure makes more sense in the 10k-1M size, where chasing pointers is expensive and the scaling doesn't dominate.