I've embraced the yo-yo, personally, but in my experiments with keto it usually takes me 2x to 3x the time length of the diet to put the weight back on as I revert to my prior eating habits. The longest I've maintained the diet for was about 3.5 months, though over the past year it's averaged closer to 1-2 months at a time. I suspect if I did it for longer or did it more extremely on the calorie-counting side my yo-yo peak would decrease -- I have a friend who went 5 months and lost 100 pounds, now he yo-yos too but his peak before he goes again is only +40 pounds instead of +100. The peak is similar to a baseline, in that if you do nothing different you'll probably remain there. (Of course that's the standard prediction if you look at it from a pure calories in / out model.)