Matthieu Ricard said he meditates 20 min. daily, Cody Rall MD with Techforpsych said he meditates 20 min daily, Yongey Mingyur Rinpoche said he mediates one hour a day.

Is this because they listened to what Richard J. Davidson writes in Altered Traits»:

But world renowned leaders in meditation give completely different numbers.

• In «Happiness» Matthieu Ricard wrote that Tibetan meditators meditate in reteats, and when they come back they meditate 4 hours a day.
• The Dalai Lama the 14th. said he mediates 5 hours a day.
• Thích Nhất Hạnh recommended on YouTube 4 hours a day.
• Yogi Bhajan recommended on YouTube to practice Yoga 4 hours a day:

at 4:38 he says:

«if you can control yourself between these two hours in the morning and two hours in the evening it is never possible that you will not have a good outlook and that you will not be satisfied and happy.»

These data are not from scientific studies, but Richard Davidson’s are. But are statements such as only a practice of 20 min. daily es enough for objectively measurable changes in a brain scanner. But is this convincing?

We suppose you can practice 20 min daily the violin and then measure changes in the brain as well. But does this make you a «leader» among the violinists? No, are you not rather a hobby violinist with 20 min or 1 hour daily practice?

And the same for meditation

So are Richard R. Davidson, Matthieu Ricard, Cody Rall MD with Techforpsych and Yongey Mingyur Rinpoche “hobby meditators” rather than guiding stars ? And aren’t all of these data investigated enough to be satisfying for scientists?