Light could only go to Andromeda and back 1000 times before the sun burns out. That's not very many times IMO. On the scale of galaxies, light is slow relative to any timescale relevant to large objects.
Tangentially, I've long wondered about sci fi like Star Trek. Namely, even with FTL, how large can your interplanetary alliance be? How far away can the parliament be? Over what distances can you defend against common enemies? Trade? Culturally exchange ideas?
I have had similar thoughts as well. Assuming FTL isn’t possible, at some point it wouldn’t make sense to have a cohesive system. Say, there’s an outpost that is 30 years away by the fastest spacecraft.
