A couple of things. Once you learn the animals, brumation is not needed at all. Not by the animals. You have heard me say this many times. Remember, I said, not required. This does not mean, anyone has to not brumate their animals. They can and will feed all winter and still lay successful clutches. Only the clutches will be larger and often more clutches.
What we see in nature is, the animals that are going to reproduce the nest season, seek the most heat in the winter, Not the highest heat, the longest available heat. They attempt to keep temp choices for the most amount of days per winter or per year. They seek, heat sinks, which are hill sides facing the sun, areas where heat is reflected to a certain area, amphitheater, areas with the most amount of winter sun, no shade, etc.
Of course, the farther you go north, the larger and more obvious these congregations become(dens).
As mentioned above, I do not believe your infertility was from feeding to long into winter. But I guess those are things you will see for yourself.
I have no doubts about your experience and intelligence. But I do warn you about prejudicing what you see. The labels and causes you are applying or making are based on your experience with "other" methods. And example of extreme prejudice is, recently, Dobry and Bluerosey posted a thread on kings living in pairs, where Dobrys kings worked together to tear apart a mouse, which he said was commonplace with varanids(it is) and was new to him with snakes. Both said that they kept their snakes together during feeding for very long periods of time. Yet, many here said, yea great, but you better take them apart, they are going to do this and that, harm eachother or consume eachother. Bluerosy said, he kept them that way for over 15 years, yet they retorted with, yea, but you better take them apart. You better feed them in separate containers, etc etc. Sir, that is prejudice from the use of "other" methods where the snakes NEVER learn to live with other snakes. The same goes for varanids, if they are raised in a solitary way, they often kill anything they come in contact with. But if they are raised together from neonates, they not only get along in a pair situation, but in groups as well. Including many males together. Which is not going to happen if raised separately. The point is, we as keepers, base our thoughts, theories, on past experiences and in many cases with new methods, it does not apply. That lesson was/is very hard on me personally.
Allowing them choices is totally based on the animals, its what is good for them. Its what they "do" or know how to do. And one more, its what they will also LEARN how to do. Remember, in nature, each individual snake HAS to learn to use its environment or perish. So you must give these animals time to Adjust, learn, something new.
You seem to be taking them as robots and totally mechanical. They are both, mechanical and they do learn. To learn with them is simple, if it works, repeat it, if it fails, do not repeat it. They also do not rationalize, that is, it must be a choice they need to make and need to make it at the time. This was explained to me by a good friend about dogs. You cannot reprimand a dog over something it did in the past, it does not think that way. You must reprimand them in the present. They are not people, they do not react or think or learn like we do.
Once you figure out the basic choices, you can then observe and learn from your animals. Then you can add more choices and learn more, you can change situations and learn more. This is all about learning what the animals can do.
The recipe method, of exact temp, hibernate/brumate, bring up, is all about US and not so much about the animals. You can force them into doing what we want and when. But its really about us.
Yes the recipe method is more predictable, but its predictable because we make them do what we want and when. Its like every year in nature is EXACTLY the same. Its not, they do what they do, in a range of weather conditions. They are designed to succeed over the range of tens of thousands of years. They make behavioral adaptions quickly, followed by physical adaptions slowly. Its the range of behavior that we are dealing with here.
Anyway, I wander again.
I do agree with you, commercial breeders is what the sweaterbox recipe mentality is for. Private keepers and breeders do not need to follow that, they could have fun and learn from their animals and support the animals in a much broader way. Its not about what people "have" to do, its a CHOICE, keepers can make. Giving them choices can be BETTER for both the keepers and the kept. Cheers