Cindyetal
Chirping
Not really sure but my gut reaction is more often the better. However, when your trying to separate ducks and other poultry into breeding groups I've read wait 2 weeks or more to be sure they weren't fertilized from a prior partner. So my guess is that sperm can last a few days at least, it doesn't have to happen every day. Currently I am having fertility issues with mine. These first eggs 3 of 11 were fertile. I have 3 males and 3 females all approaching 2 years, and two females that hatched last spring. I tried a method of heat treating eggs in storage (to prolong shelf life) so that also could be the problem instead of helping. I don't think there is a magic number of eggs but you may put the 3 ceramic and later add 1 or 2 of your older eggs (as a possible sacrifice) to provoke her to set.