What I gather from Doug Kraft and Bhante Vimalaramsi is that the jhanas are not as unattainable as we think. The Buddha simply would not have taught them if they were unattainable.
I canāt say for sure, but it is possible that there are grades of Jhana, but from my experience, what Doug explains in the series on his Easing Awake youtube channel and what Bhante Vimalaramsi explains in his dhamma talks on his youtube channel, I have experienced the 3rd jhana many many times. I canāt say for sure about the others, but I have had some experiences of there being nothing inside and Iām not sure if this is the 7th jhana or not.
In Leigh Brasingtonās book, he says it is possible to skip jhanas, say from 4th to 6th, for example.
Here is an explanation of the instructions for entering the 1st jhana by Leigh Brasington.
The thing I know is that this topic doesnāt need to be as nebulous or hyper analysed as it is. We can experience Jhana, it does have an affect on our lives, but there are levels of jhana from what I understand (experience and fruit?).
All I can say for sure is that longer meditations are needed to access jhana and it has to be consistent every day for any chance at getting there. In my experience, it takes minimum 45 minutes to get there and the cumulative effect of daily long sits increases the likelihood of reaching a jhanic state.
The Buddha taught this path that is hard, but attainable. We need to be mindful all day long to make it easier to get somewhere in our meditations when we sit down in stillness. We need to sit daily, at least twice a day and for minimum 30 minutes to 45 or long per session to make and serious progress, although there is benefit to any amount of meditation.
The other thing I know is, we canāt know what someone elseās experience is and we should seek counsel of those who have great experience in meditation (could be exceptional lay teachers like Doug Kraft or Leigh Brasington also). Bhante Vimalaramsi knows things and reads the suttas in ways I have not heard many monastics talk about things and that tells me that he has experience in the jhanas and not just from reading about them.
The best thing we can do is actually get to work. The Buddha extolled a sense of urgency in the practice. Every moment counts and over thinking the practice is not practice. Itās like thinking about playing hockey and playing hockey being a completely different experience. We must get on the ice and skate and in this sense get on our cushion and meditation with great zeal and effort (gentle but great effort).
https://www.accesstoinsight.org/tipitaka/kn/thag/thag.01.00x.than.html#passage-39
Tissa (Thag 1.39) {Thag 39}
As if struck by a sword,
as if his head were on fire,
a monk should live the wandering life
ā mindful ā
for the abandoning of sensual passion.
This is a reminder for me. To sit more, to dedicate more of my life and energy to mindfulness and meditation so I can reach the Jhanas with some regularity and therefore purify my mind.
We are here together, supporting each other and so we are stronger together, but we must all do our own work.
I wish anyone reading this great luck, motivation, energy and success in their meditation as I wish this for myself.
May we all reach the end goal in this lifetime. Who knows what the next life will bring if we donāt make it out of Samsara.
Metta