The respawn times in both Seb and Chardok should be improved as of the last update, you may want to check it out and give any feedback that you may have.
I would agree that the spawn times on Karnors were pretty fast at launch, but they were slowed down since then as well. I'll try and do a run there this week and see if I can get a feel for where we are at now again and see if I need to adjust it more.
LINK
(Saavedra) Re:do Mobs respawn too fast in the new shared dungeons (Seb, Chardok and KC)
