You’re so funny. A not-napping kid not sustainable! Not a single one of my kids napped after 14 months. Not all have ADHD.
I count myself lucky. I didn’t nap after 6 months. Neither did my uncle.
I didn’t “sleep train” my kids. I wouldn’t ever do that. I co-slept until they could make it 6 hours without nursing because mom NEEDS sleep, too. Then they started out in the crib and I got them if they cranked up into a real cry. Nurse, put back if I’m still awake. We all got sleep that way. They slept 6 hours right on time, then 8 hours, then 10, then 12. But they stopped napping if they were going to sleep at night.