The subjects of the studies in question really have done 1000s of hours of actual meditation 'practice', ie. sitting down (also lying down & walking) and going

The subjects of the studies in question really have done 1000s of hours of actual meditation 'practice', ie. sitting down (also lying down & walking) and going through programmatic sequences of meditation exercises. It is true that some traditions (including the burgeoning recent trend of secular meditation) emphasise mindfulness in daily life, particularly for lay persons. But the studies showing huge differences in mental activity have done so in 'Olympic-level meditators'. These people have made deliberate meditation practice the focus of their lives.