Day 28 for my duck eggs, some internal pip, some not

[Alaskaduck]

It's my first time incubating and I'm wondering how long it should take from internal pip to external? I have 8 Welsh Harlequins and at least 3 have internally piped. How much time should they take to pip externally? Today is day 28. Is love any support I can get

 

[Tlmcq]

Ducklings take patience and more patience when hatching...They can take a very long time to hatch. Days from start of internal pip to finish of zipping and hatch is not unlikely.

 

[Alaskaduck]

Thank you! I can do patience