I'd honestly say a combination of both. I'll explain my thought. You're right that they are very very smart. And my birds would do the "if we ignore her she will go away" routine. But also they do see that hand=no hurt+brings food==OK.
What I would recommend is not do the millet, taming sessions along side of feeding time. So, maybe if you feed them in the morning (I do too) then do the taming session in the evening.
My schedule is, morning, feed pellets and seed, I work all day, I come home and feed them their eggfood/veggies (they are molting so its eggfood). Since they are in my office while they eat that I just hang out in there and surf the web LOL. Then after they have had that available for 2 ish hours and are full and happy. They like to play for a bit. THEN I do the hand taming session with them. Sometimes I do the hand taming sessions before I feed in the evenings.
On the weekends I mix it up and do the hand taming sessions in the afternoons between feedings.
Also, Id like to add. Something I read on here and have changed. I have multiple food bowls in both my cages. I have one that is filled full with ONLY pellets. Its always kept full and always available to them in their cage. It sat untouched for weeks LOL. I also just left it, untouched. But now they eat it. Actually sometimes over the seed!
My morning feeding is to add a second bowl to their cage with just seed in it for them. When I get home in the evening I dump that and put the eggfood/veggies in that same bowl.
Make sense LOL!
Edited to add: My birds are not all the way tame. But they do readily come eat millet from my hands, as well as step up to let me take them from the cage and put them back after play time. Its been 3 months. So making progress