Sorry if this breaks some rule about talking about attainments.
I’ve heard of people ‘getting’ jhana in a matter of months. (I’m not sure if that means touching on the state of having on-demand mastery.)
If a meditator practices an hour or two a day, how long does it usually take them to get 1st jhana reliably, for example? And then how long to move up through the other ones?
What has been your experience of working with people on the path?
The Visuddhimagga mentions if a person practices an unsuitable meditation object, the progress may be slow and difficult. Nowadays mindfulness of breathing is the most taught method but many people may be of greed temperament. If they enjoy sensual pleasures a lot and are easily attached to people they meet and just want an easy life in the deva or Brahma world in the next life, they are probably of greed temperament. Also, if a person is young like in their 20s, they may have a lot of lust. Asubha is a great meditation method that is suitable for those with greed temperament and should be taught more in my opinion.
I’d recommend reading the Visuddhimagga from beginning to end. It has a lot of interesting details.
Here is a pdf that shows Asubha pictures.
The time it takes to attain and master jhana can vary. It’s not always about how talented someone is. It depends on what meditation object you practice, your temperament, environment, and defilements.
If I remember correctly, Earth Kasina is suitable for all temperaments. It’s also the first meditation object that the Visuddhimagga teaches. I think it should be the main meditation object taught in monasteries.