When to stop trying?

Since September I have been introducing one of my males and females. They locked up pretty quickly. The female is 5 years old and has had a clutch before. The male is 2, going on to 3 this summer. I introduce them about once ever 3-4 weeks. They see each other for about 24 hours. I separate them after I see lock and it usually does not take long for them to lock up. Within 24 hours they are done and the male goes home.

The female still shows no signs of building or ovulation, staying 100% on the warm side and she is still eating like a horse. I was told the food refusal was a good sign but she still eats.

Could it still happen at all? Is there a time when you stop introducing the male? Not really sure what to do at this point. Any advice?

It could totally still happen. It's just my observation, but I believe females will sometimes lock with a male in advance of cycling. Maybe to test him and decide whether or not they "like" him, maybe to collect backup sperm to hedge their bets. If she's eating like a horse, that's good in my book. Females who "want" to add the reserves needed to build follicles can be absolutely ravenous.

Would I stop introducing the male? Nope. The only times I stop introducing, are when he loses interest in her (I should note, I have only one female in whom this is a reliable indicator), or I see an obvious ovulation. And even as a winter breeder, I typically don't see ovulation in my girls until April/May/June.

It's only January. There is plenty of time. :)