Shifting is an OBE, this means that in order to achieve it you have to travel for a short period of time through the 4D (A.K.A. astral realm). Shifting is the process of moving your consciousness to another reality. To do this you have to be in trance state, meditative state or theta state (is all the same but with different names), because you have to go inside your subconscious where all the dimensions exist (even this one, the physical realm).
Your subconscious is another name to refer to your SOUL.
Your conscious is another name to refer to your THOUGHTS, EMOTIONS, ETC.
A piece of your subconscious and your conscious exists in infinite realities. You have to acknowledge that YOU aren't your subconscious nor your conscious. YOU, your conscious and your subconscious only share the same current vessel (body) and this reality. But you aren't neither of them, you only co-exist together in this CR. YOU exist outside of them.
There are infinite versions and combinations of your conscious and subconscious.
What you are trying to move is your consciousness, your awareness, your perception of what YOU (from infinite ones) you want to experience.
When you shift to a different reality, your conscious and subconscious are different from your CR ones because in that new reality you have experienced different things, so your personality, thoughts, blockages, resistance from your subconscious is all going to be different; it's going to be adapted to the new reality but YOU will still be YOU because, again, you aren't your conscious nor your subconscious. If you want to keep the same conscious and subconscious you have to script it.
Your conscious is your personality, thoughts, emotions, etc., it's a combination of your genetics and environment. Since in that new reality you will probably have different genetics or different environment (or background) you won't be the same person, the same thing happens with the subconscious. If you had different life experiences your subconscious will behave according to those life experiences; you will have more or less blockages or resistance to manifest things, your ego mind will be different, etc.
When you shift you acquire a new conscious and subconscious but also the memories, desires, etc. of that version of YOU. If you want to keep your memories and desires from your CR you have to script it.
This is why you can't script what your version of YOU (A.K.A. clone) is going to do in your absence, because they have their own conscious and subconscious. Infinite versions of YOU (A.K.A. clones) exists, there isn't an "original one", all of them are YOU. You just have to move your consciousness, awareness, perception of what YOU want to experience.
When people think about visualizing, they think that they are imagining their DR, but in reality, what they are doing is seeing, in their minds eyes, their DR; mentally, you are there. If you ever try visualizing in trance state, meditative state, theta state, you will see how it's easier to do or how your mind alone starts making new scenarios and stuff like that. That is because you can use your mind's eye to experience your DR, and since shifting is an OBE, and you have to be in trance state, meditative state, theta state to do it, when you visualize in that state and kinda get lost on it and it becomes more vivid, it's because you are more there than here. When the images get clearer, or you can hear things or smell things or feel things (emotionally or physically) that aren't from your CR is because you are starting to move your consciousness, awareness, the perception of YOU that you want to experience to your DR, and you are probably more there than here. When you start getting shifting symptoms it's because you are starting to separate your consciousness from your CR and going to your DR (you are at the beginning or maybe even in the middle of both realities), if your symptoms intensifies it's because you are moving to your DR. Through the shifting process your are in the 4D (A.K.A astral realm), when you get symptoms and then they intensify and start experiencing things from your DR, all those things happen in the 4D.
And for people with aphantasia. Aphantasia is the inability to create images in your head VOLUNTARY, this means that you do it involuntary. It's more like a limiting belief. You can force your subconscious to let you visualize or you can experience your DR in your mind, the same way a blind person experiences their lives. I will make more research on this topic to see if I can find a solution to it :/.
I think that the keys for shifting are trying the methods without the expectation of shifting (if for some reason you don't do it you don't get disappointed) and when you are doing any method you should focus on trying to experience your DR in your mind's eye and don't think, just try to be there. Avoid thinking.
They are all the same thing and we experience it before falling asleep and right when we wake up. I think it's better to shift at night, while being super tired (physically tired, mentally awake). Most of the methods say that you should go to sleep after getting symptoms but I think you should keep visualizing your DR until you open your eyes (you will open your eyes when you are there involuntarily). Something that may happen is that you get so lost in visualizing your DR that you'll think that you've fallen asleep but in reality you are just going there. Something that can also happen is that you wake up and start feeling symptoms, keep doing the same (visualizing, trying to get lost in your DR). AND STOP THINKING, THINKING IS PREVENTING YOUR FROM SHIFTING. THE KEY FOR SHIFTING AND ASTRAL PROJECTION IS FEELING THE SYMPTOMS (ASTRAL PROJECTION) AND FEELING/ EXPERIENCING YOUR DR (SHIFTING), NOT THINKING. WHEN YOU THINK, THE EGO MIND/LOGICAL MIND WILL START TO ACT UP AND FUCK EVERYTHING UP SO, AVOID THINKING.