Hi there and welcome to BYC!
No, I wouldn't say it's malarky. But I would say that that there aren't MANY rules in chicken keeping.. just a bunch of best suggestions.
My first hatches were super high % maybe even 100.
Genetics, eggs shell color, shell thickness, age of eggs set, age/breed/nutrition of parent stock, ambient humidity, and perception there of verses personal hydration levels are all variables that matter SOME.. in addition to pure luck! But yes temperature is possibly THE most important factor. Congrats on your hatch!
Did you use a hygrometer at all? Honestly I rarely do. I agree with your finding that high humidity rates are NOT always a good choice or required and sometimes even more harmful.. noting that when you start doing hatch analysis like what's left in the eggs shell after hatch, where it pipped/zipped, down/naval condition, and other things like that.. it MAY point to thing that CAN dial a persons hatch parameters in as good as possible.. But, LIFE does find a way quite often! One of my favorite incubation/hatching resources aside from BYC of course..
Incubation guide
Small batch numbers RARELY correlate to larger sample sizes and this is likely what you will find as well. Glad to have another thinker/questioner and searcher for the truth in the community! I hope you will keep long term records including at least ambient humidity reported by the weather station for your location and consider starting threads and/or writing up some informative articles like this one on dry hatching..
https://www.backyardchickens.com/ar...h-eggs-using-the-dry-incubation-method.47694/
The more breeds I work with the easier it is to face different challenges,
guaranteed. After hatching literally hundreds of chicks, it would be nice if all hatches came out that well with such little effort.. automating things like turner REDUCES hatch rate also. Sometimes keeping it simple works wonderfully, thank you for sharing.
