hrmmmm
Tactics Trainer "math"

Don't expect retro-active fixing of rating mistakes. Your tactics trainer rating -- like any ratings -- goes towards its true value the more you play, regardless of what happened in the past.

Well, I guess you could let the past be what it is, and simply apply the sum of all your recorded rating adjustments to 1200 to create a new rating going forward. But given that the result would probably fall somewhere within the 600-point range my rating dances around in weekly, it would hardly matter.
Erik, that is a good Rorschach impression. Jay, thanks much; I'll give "Stop only if I fail a problem" another try after the next release, and I'll be sure to check the math every once in a while as I go. Cheers!
I've seen this before, but I'd forgotten about it... I more or less *have* to "Stop after each problem" in Trainer because when I use the "keep 'em coming" options, Trainer develops numeracy problems. The fourth column is my rating.
1611 + 43 = 1654 ✔
1654 + 31 = 1685 ✔
1685 + 32 = 1686 ✖
It's as if it KNEW that all I wanted to do was hit the 1700s before dinner.