How long are my eggs safe? Chickens & Ducks

[Duckshack]

I have a few questions about the eggs and consumption of them.
I retrieve eggs from the coop once a day where my chickens and ducks coexist. Should I be retrieving more than 1x a day? From the time I retrieve the eggs wash them and refrigerate them - how long before they are spoiled or not good to sell?

 

[ChickenCanoe]

The only time I collect more than once a day is if weather is freezing or extremely hot.
If selling eggs, I'd probably sell them less than 3 weeks old.
Since you have ducks, am I right to assume the eggs get muddy?
If not, there really isn't a need to wash or refrigerate them. Washing removes the cuticle protecting the contents from bacteria. Eggs in grocery stores have been washed so they must be refrigerated.
Many other countries don't require washing and the eggs can be found on the store shelves unrefrigerated.
Mother Earth News did a study and they found the best way to store eggs long term was to leave them unwashed in a sealed refrigerated container. They lasted 7 months that way. Read through to the conclusions of the experiment.
https://www.motherearthnews.com/real-food/how-to-store-fresh-eggs-zmaz77ndzgoe