... Before she's out?

What criteria do folks use to decide when to cull a female from breeding due to low fertility?

I have a nice female normal that I've tried breeding two years in a row now -- multiple confirmed locks to a proven fertile male -- and she hasn't laid either year.

Now, if she were, say, a coral glow, I would probably give her every season until forever to get her act together because her color gene would be valuable enough to overlook the poor breeding record. This is a normal, though, and I have extremely strict standards for normals (must eat F/T like a retic, must have an exceptional pattern and color, and must be highly fertile!)

I'm thinking no more than two strikes for a normal, maybe three for a more common morph like a pastel or spider, and as many as she needs for something more genetically valuable ... What are others' cull criteria for poor-breeder females?