The "path" in Dzogchen is not like "path" in other systems, where you start out from point a and wind up at point b.
The "path" of Dzogchen is simple removing the jaundice of ignorance so you see what is there all along from the beginning. It is not about acquiring something new you did have before.
Well I don’t see many differences in the 3 Teachings, I am convinced that they are interdependent.
Also one can reach Dzogchen step by step. Herewith is thought of people with a lower level of understanding. Herewith do I mean myself as an example where I did reached Dzogchen over a more gradual Path of interdependency.
I got in Sutra result, in Tantra and finally in Dzogchen. This was done with the help of a gradual better knowing / understanding of mind and mind.
To remove ignorance, well here we have a wide range of means and to get ignorance cleared that is possible in all the 3 Teachings. Gradual seen is the mind cleaned little by little.
Regarding the Ngondro, I can agree that for some 10 prostrations are enough, in case of older people like my mom. The total amount of repetitions can be reduced as soon as there is result coming. Then do come the Rushens in the same way.
Tokden Drime Yungdrung Rinpoche, is for me then also an example as someone who did reached with his practice the Rainbow Body in 2002. Here one can watch that what Mutsog did also wrote about Lopon Tenzin Namdak’ s spiritual behavior, which is also in agreement with TDYR.
So for me and other Bonpos is it not strange to get to Dzogchen over a gradual way, it is part of our tradition.
Will recommend JL’s comments as a further elucidation to my point of view.
JL wrote once:
To envision properly the Paths of Sutras, Tantras and Dzogchen, my root-master said :
"Look at how Zhinay aims at concentrating and stabilizing your mind ;
look at how Kyerim is a way of concentrating and stabilizing your mind to a much higher level with the various visualizations;
then look at how Trekchö is a way of cultivating and stablilizing the experience of the Natural State. Do you see the progression ?
Then, look at how Lhagthong aims at your integrating movements and piercing the real nature of things; then look at how the various kinds of Dzogrim aim at the same thing but with deeper means; then look at Thogel and see how you can integrate the Tsel of your own nature. Do you see the progression (or parallel)?
This is what we mean by Meditation of the 3 Vehicles (i.e. Sutras, Tantras and Dzogchen). If you see contradictions, you are grasping at elaborations. If you don't see contradictions, you are understanding the real purpose (or : intent) of the teachings.
If this dawns clearly in your mind, then you understand that the Training in Ethics is necessary for the Training in Meditation and that without the latter, there is no Training in Wisdom. This is the reason why the teachings of the Buddhas are entirely perfect (yongs su rdzogs) in all their Vehicles."
After reading Shardza throughout and studying what his masters had him study, I am not so sure anymore about the differences in the 3 teachings.
Some reasons are that :
1. the basics of Sutras are true throughout the entirety of the Path,
2. the daily practice of Tantra is possible outside retreats,
3. the correct, authentic practice of Dzogchen is to be done in retreat only.
So, Tokden Rinpoche Drime Yungdrung, a highly realized master who did Rainbow Body in 2002 (and who taught Lopon Tenzin Namdak Rinpoche a year before his passing away) declared :
"My ethical conduct is that of a sutra practitioner,
my practice is that of the Yidam (tantra),
my View is that of Dzogchen (kadag + lhundrup)."