I stand corrected. Yes, I am using "Yangti" in its commonly held meaning, as dark retreat, in the DC. Of course it is a body of work as you mention.
As to the 3000 becoming Buddhas, we differ in our interpretation and understanding. I think it means many, but perhaps limited to around 3000.
Of course there are many different dark retreats and I am referring specifically to that taught in the DC. I've read some translations of the Bon version, and I am content that although the techniques are different, that the results are similar. When I researched the Bon system, many years ago, I found that they do not have such a comfortable place to practice, as Tsegyalgar. I am lazy and like my comforts, and was very happy to do my 49 days in the dark retreat "Hilton," with a trusted attendant, flush toilet, good air circulation, a well stocked refrigerator, clean, and plentyful water and a place to prepare food.
Yes, the first vision is easier than the others in Togal, and that is why I was very happy when I discovered how easy it is to make progress in the dark retreat, in comparison. Maybe I will get back to Togal someday, but I don't feel any pressure to do so. I am content.
The key point is don't be afraid to try, and of course - go for all the boosters you can get. What you are calling "Boosters", I am calling the "ney," or the keys that unlock the practice. These are what are given by your Teacher in oral tradition, and are not necessarily the same for everyone. I am content with what I have received both for Togal and Yangti. Sure you can research ALL the sources in the Tibetan corpus, or go around collecting all the "boosters," but in the end it only takes one practice to relax your mind into Awareness. Awareness has no grasping, rejection, or dimension, and is content in itself. Even bliss, clarity, vastness, and luminosity are imputations from the intellect and have no sticking point in Awareness.
Being able to "Transmit," to help the 3000, now that is something else.
Actually, maybe it is an important number because that could help explain why the DC webcasts, and the DI via webcasts, have stuck around this number, despite ChNNR teaching in the West for over 40 years.
Perhaps the key point is to practice a little after gathering the information.
The happy idiot,