With how much harder the weekly grind is on manga authors as they get older, would only see Gotoge, Furudate, and Horikoshi return in a monthly serialization regimen.
Kishimoto and Akira Amano seem fine in their non weekly regimens for their subsequent hit manga.
Both gotouge and furudate seemed quite healthy at the end of their manga.
Furudate took only 2 breaks(I think) during haikyuus entire run and was able to do covers and color pages very frequently.
Gotouge never took a break during demon slayer with frequent covers and color pages and was described in an interview to have a high amount of work ethic.
Also there have been many cases of 40+ year old veterans starting new manga in wsj
•Yusei Matsui returned to jump when he was 42 with the elusive samurai
•Kenta Shinohara was 47 when witch watch started
•Tadatoshi fujimaki was 40 when kill blue started
•Kawada was ~40 when martial master asumi started
•Ken wakui is probably over 40 years old
•Mitsutoshi Shimabukuro was 44 when build king started
•Kentaro Yabuki was 40 when ayakashi triangle started.
•Ryuhei Tamura was 40 when cop and dolphin started.
And many more...