You are welcome! Just don't forget to come back.
I did it, but I really think it depends on the breeds. And of course, ducks take a week longer to hatch than chickens, so stagger accordingly.
Shell conditions play a big part. I won't likely incubate my duck eggs with any bantam eggs again, because the bantams lose moisture quicker.
But yes, 30ish should work with ducks also, just watch your air cells. I'd also recommend reading up on misting duck eggs during incubation! I haven't done it, but I think I will next time.