When I say that rebirth is metaphorical... what I really mean is that there is no literal self that gets reborn. In this way, I can see it in every moment, and every life. I also can imagine this for every expansion and contraction of a world, or every kalpa... but I don't really try to run with this, because it's a papañca, or a big diffusion.
I think it's like a fractal. It's really a matter of finding out what the useful zoom is (a focus) for one's own practice, which will lead to a complete unbinding. For some it's moments, and for others it's lives.
The Dhamma that we're studying right now (based around the paticca samuppada) was specifically designed for a human life, by the Buddha. This is what a practitioner really should focus on, to make any progress with it. What does the humans have? They have moments, and lives... those should be studied.