@sweetlvr4u :O oh dear, you are wrong and i was wrong too! i should have double and triple checked my work. i pulled those dates from the wrong chart. those were the JAPANESE publishing dates for the MANGA. damn! here is the corrected quote for the Japanese dates for the LIGHT NOVELS.
1 February 10, 2017
2 September 8, 2017
3 October 10, 2018
4 May 10, 2019
5 February 10, 2020
6 September 10, 2020
7 May 8, 2021
8 March 10, 2022
9 March 10, 2023
first 2 Volumes in one year, yet again i was probably right the WN had enough content for 2 physical books. 1 year 1 month gap between Vols. 2 and 3. 7-month gap between Vols. 3 and 4. 9-month gap between Vols. 4 and 5. Vols. 5 and 6 were in the same year with a 7-month gap. 8-month gap between Vols. 6 and 7. 10-month gap between Vols. 7 and 8. finally, EXACTLY 1 year gap between Vols. 8 and 9. so your average is still incorrect since Vols. 2 and 3 then 8 and 9 had a 1-year gap apiece.
actually, fin is French for End, Fine (or good or excellent), Close (as in a door), Back (as in butt, ass, rear, the back of a book/page other physical object), Termination (as, in the end, like 'the end of May'). using it at the conclusion of a film HAS been an implication for around a century the FILM itself was at an end. NOT the serial that film was a piece of. you need to study your film history AND your French with a lil more attention to detail.
continued to publish online? that is peculiar. most authors are contractually forbidden from continuing PUBLIC WN work on a project already sold to a publisher. ah well, somebody had a better lawyer than the publisher this time.
with love is war, each time fin has appeared except for the movie 'First Kiss'... we got a sequel. did you forget this?
now let us compare anime release dates.
S1 April 2021.
S2 October 2023.
therefore, they had access to Vols. 1-6 for S1 and Vols. 7 and 8 for S2. if you're right on the split at Vols. 4 and 5 for S1 end and S2 start, Studio Diomedea worked on this project continuously.
next, an exploration of that continuous production schedule possibility for Diomedea. S1 of Saint ended June 2021 ONE MONTH after Saint LN Vol. 7 was published. Futsal Boys ran from Jan.-Mar. 2022, then came Isekai Yakkyoku from Jul.-Sep. 2022, next was Tensei Oujo to Tensai Reijou no Mahou Kakumei from Jan.-Mar. 2023 starting RIGHT AFTER Saint Vol. 8 was published, and finally Saint S2 was simultaneously released alongside Kamonohashi Ron no Kindan Suiri back in Oct. it does look complex but, if Diomedea did the work on Saint S2 piecemeal in-between other projects? it looks possible.