for me, there are certain kavas...or certain nights with certain kavas...where i can get the jittery feeling 2-3 shells in and after it passes, it's all good. i can use the same kava another night and it won't happen, but still some are more likely to cause it than others. it almost never happebs to me on the first shell though. I remember a time that it did, BKH used to have a different melo melo several years ago and one shell of that, the 1st time i had it, felt like drinking 3 big fresh shells in vanuatu...or like drinking a few ml of ghb or something.It didn't happen like that every night though...there might be a few other times where first shells have done that to me, but there's more night where it's been the 2nd or 3rd shell. For the most part, it doesn't happen to me. I gravitate toward balanced or balanced/heavy cultivars so that might be why it doesn't happen to me often. I also think there's a genetic aspect to how certain kavalactones behave in an individual that can be somewhat different from someone else.