I can confirm that, for me, it is really about repetition. I’ve spent the last two weeks practicing nothing but the Sonatina, mainly focused on the first allegro section.
When I got to work particular parts, for instance that G Major scale run that’s been trolling me, I look at my hand to analyze my technique, and then continue on with the piece, still watching my right hand, but unbeknownst to me, I’m playing both hands without looking at the music. So I can confirm, for myself, that it’s just repetition of practice, but also not forcing myself to memorize.
At least I’ve settled that issue with myself. I’ll try to not to repeat myself. 🙂