I've used them a few times a day, just to learn what's going on. And now I know. Sort of the same with weighing - lots of people are against weighing every day, but I do it because I know I fluctuate a lot and I want to know what the pattern is. Also, I think it would be discouraging if you weighed say, Friday, and while you were actually losing you ate too much sodium (or something) on Thursday, and your scale Friday shows a bunch of water weight - I'd rather know exactly what my body is doing. Anyway, the keto thing is interesting but I assume if my carbs are under 20 I must be in ketosis.
And things are going fine, by the way, this was the end of day four with no problems.