I get consistent 100% scores on D2B so I think I'll use D3B as a 'learning' level. I'm still trying to figure out the right 'thinking' strategy to use for D3+B. With D2B I just empty my mind, look at the cross and 'just press the right answer'. But that doesn't work reliably for me on D3B. I seem to go better actively rehearsing the sequences in my mind and explicitly forming a picture of what historical item fits 'next'. My performance is wildly variable (30% to 80%) and depends massively on whether my brain gets in the right zone.

I'm already noticing my brain modifying itself in response to the training. My competitive instincts take control and whenever they spot any unhelpful thinking they throw it out. Distractions, anxieties, frustration at making mistakes, none of these help it win and the brain can identify that right there in the short term. So all the habits of mental hygiene that I have worked to develop for myself get magnified.