I don’t know anything about this topic so anything I say is complete speculation. My theory is that time acceleration is our way of coping with stress. The older we get, the more complicated our lives become and this results in stress. The brain probably uses some mechanism to allow us to forget some of the stress - and in the process - time seems to accelerate. My evidence for this is parenthood. The first five years of raising a child are so stressful on the body and the mind that they seem to go by faster than the time that follows, at least that’s how it feels to me. We say “they grow up so fast” because our brains helped us cope with the significant change that comes with child care.

As for outside of just having kids, the sameness of daily routing is likely carving out a mental shortcut so we don’t need to focus on it much. Think of it like a path you walk over and over, at first it’s new and barely visible then slowly becomes pronounced, well traveled. We don’t think about that walk for the 1000th time because it lost all wonder by walk 5 or 10. It just becomes something to get through. I think this is how the daily routine work in our minds and why we forget the day. As a kid, that path hasn’t been travelled as much so it’s wondrous and exciting. You take more moments to take it all in.

By this logic, I would assume that doing more new things more often would slow down the passing of time. Maybe someone has done many new things all the time and can anecdotally verify if this is the case or not. I certainly can’t.

But this is all theory based on speculation. I’d love to get some real insights into how it actually works.