Anyone else have effects of a certain kind of kava change after only a couple of uses?
I have, definitely.
In my experiences it's usually because it was a different harvest or batch of the same brand or variety. Or, it was something inherent in the nature of that kava, e.g. I and others have experienced with Tongan Family Reserve that it is a strong kava (and an excellent one!) and the first time you drink it, you get this incredible heady euphoria. But only the first time. Subsequent sessions are extremely pleasant, it is a fantastic kava. But that euphoria is not there.
OTOH, My first sesh with Eua was very nice but not especially noteable. Real good, don't get me wrong, very good and worth the price but not "impressive." But..... the second sesh with it was better, and the third better than that, and the fourth.... And the character was different, too, more depth to the headiness and that was all from the same batch. I have noticed, also, that while the flavour of a kava didn't change, the way I experienced it did. First four shells of nangol I couldn't stand the taste althugh effects were great, but by the 5th shell I loved it. It was the same prep. I loved my first prep of nambawan, but the second I loved even more. It was the same taste, but I had changed.
Then there's Squanch. Only has two modes: as good as the last time or "even better." About the most consistent kava experience I've found, never disappoints, never apologizes, just Squanches on.
And, of course, there's mood and setting and time of day and food in stomach, all variables which I rigidly control in the name of science, even to the extent of consistently replacing toilet paper rolls in the dispenser the right way, lest a glitch in the universe should affect my sacred krunk. Sorry, I wrote that last sentence under the guidance of nambawan. I'm innocent. I swear.