Picture taken straight from my account at TreasuryDirect. I know that i-bond interest rates reset every 6 months but it looks like bonds issued in April and October get special treatment? Seeing this, I'm not sure why I wouldn't just make two purchases a year, only in April and October, and reap almost double the gains? I feel like I'm missing something obvious here.
Of course I just happened to look at my account when there was only one "tranche" of bonds that hadn't adjusted and it looked like there was a weird pattern going on. Thanks for clarifying!