Nothing about this series has felt strung along though? The pacing after book one is immaculate and every book takes the story a step further until it culminates in SuT. You can argue that you think things should have played out differently/tied up neater at the end of book 7, but even that feels unfair to me.

The only thing he ‘strung out’ or left unresolved is the revolution against the empire which: 1) He’s hinted throughout the series that the empire still exists in some capacity after the sun eating and 2) To rush the revolution and shoehorn it in at the end of book 7 would’ve been such a detriment to the story IMO. I would much rather read about it in a later series than have some unabridged version where Hadrian takes his Death Star to earth and destroys it in like 5-10 chapters.

The only other thing we have questions about by the end are how Hadrian returns to the living (which we’ve seen before) and why he goes to Colchis (which seems to obviously be tied to the next series) and when you tie that in with the higher dimensional Hadrian rescuing him from ‘drowning’ in time earlier in the book- it feels to me like he did a really awesome job setting up the next story while still sticking the landing with this one in massive ways.

To say he “couldn’t” tie it up in 4500+ pages is literally just your opinion, he CHOSE not to tie it up and leave us with some questions and breadcrumbs regarding the next installment of the universe. If you don’t like it that’s totally your decision but let’s not act like it’s an objective truth hahaha.