Though you definitely didn’t ask me with my on/off style, it’s very noticeable for me that the longer I keep my (non-animal net) carbs extreme low, the better I handle carbs. If I had a carni week, I can eat lots of sugar (and lots of fat and protein with them but I couldn’t avoit that if I tried, they are basic) and I feel nearly as well as on carnivore (sometimes exactly but the type of carbs matter a lot*). (If I continue eating like that, I get sugar poisoned but it takes a somewhat long time, I crave carnivore and bounce back way earlier). My body gets more rest from carbs and can handle more, I suppose. But not everyone is like this, to put it lightly. I even read some persuasive articles about never to shock our body with high-carb right out of keto, it was very logical, I just don’t seem to function like that.
No idea what my BS does but I don’t even care, it’s my body’s job to keep it in the right range all the time and it does just that, at least I don’t notice it wouldn’t. Except maybe if I do something insane (like eating sugar alone. like very sweet fruits) but I don’t do that anymore.
*The type of the carby item matters A LOT. I met some ice cream that made even my high-carber SO a bit unwell… My body responds worst to overprocessed sugary things too. Hence I avoid those. It wouldn’t do me ANY good. Bad idea. I have way better food so I keep my curiosity in check.
Ice cream is best when it’s carnivore (or at least keto, I do adore bananas… I used it in my dairy free ice cream in the past. whipped cream substitutes it well enough) if you ask me
Ice cream is ALL about being cold, yolks and dairy, after all. At least IMO 
So… You need to figure out things for yourself. We aren’t the same (even I am not the same I was years ago) and different carby dishes may have a very different effect on us. I may handle one kind of sugary ice cream and not another. I know this because a relative often offers some to us and I am curious and even rebellious there so I tried it sometimes. Well, did in the past, I don’t do it anymore, it just doesn’t worth it. I lose absolutely nothing with avoidance, in the contrary.
I know many carnivores get sick if they just eat a tiny plant… No wonder as people who can handle keto level carbs just fine tend not to restrict themselves as much as carnivore demands. At least I have read that many times that carnivores very often do it out of necessity. But I saw that from ketoers a lot too. And I have read about ketoers going off and getting quite sick - though some can jump back into high-carb without getting sugar poisoned (at least not to the level to stop). So, individual as usual.