I am “abnormal” as I did keto, got fat adapted, went back to my old low-carb ways but kept and improved some keto habits and I am on and off since (but I continue to change my ways a bit). Now very low-carb became possible and it’s too tempting so I don’t plan to stray from it often.
I started with 40g net carbs in the very beginning as it was extremely little even after a few 80g years, anything below was totally unrealistic. I was a huge vegetable lover and well, vegetables are carby especially in my big amounts (to be clear, I felt I eat less than minimal amount of vegetables at 40g. I almost completely stopped eating vegetable dishes as those couldn’t fit, it was a tad tough without meat, I usually did vegetarian keto). I almost never went below 30g until recently, for various reasons.
On my carnivore trial I eat 5-10g net carbs (total isn’t much more). I probably will do almost carnivore a lot and go a bit higher but not very much. I don’t know yet if 20g would work and I won’t experiment with that now. My new intake being so low, I don’t even need to track and I stay in ketosis, that’s great.
My personal ketosis limit is around 45g as far as I can tell, I didn’t notice it changed any. I am quite sure about it as there were signs it works but I don’t measure anything and I actually don’t even care so very much about ketosis. It’s probably great and whatnot but my main priority is being healthy and feeling great, whatever it takes. I tried this and that and extreme low-carb seems the best now. But I usually feel fine if I don’t go over 80g net carbs (or don’t eat super wrong items) and it’s very easy and natural to do, very nearly always. I am a low-carber for life, it’s clear since several years and I am very pleased with it.