I'll chip in as well
First, take a look at this:

You can see that Reimu is standing in a "coffin" shaped space that is much smaller than the "diamond" space to the left.
Now, this is not necessarily a bad decision, as the position of the metal fatigue bullets make the coffin space very safe.
The important thing is:
1. Do NOT stand in the coffin space right under Remillia if she has moved down the screen (i.e. to her vertical position in her first wave); you probably would have to squeeze through very small gaps between the laser and the bullets. It's okay if it were a diamond space though.
2. Standing in a diamond space may be a bad idea if you will be too far up the screen
3. Don't stand in the triangular space near the bottom unless you have to (i.e. ran out of time to move and got stuck).
The next step is reading ahead to see where in the laser space you should stand in <-- you have very little time for this.
Sometimes, this is hard, as both sides have very narrow gaps (in which case you probably picked the wrong laser space to stand in, but too late), in which case only experience can help you.
As seen in the next picture, you should NOT stand on the right side of the coffin space or else you are walled.
Similarly, if you were standing in the diamond space, you should slightly right and brace yourself to go between metal fatigue bullets.
(Alternatively, stand near the middle of the space and go to the gap between the metal fatigue and the bubble).

Since we have read correctly, we are now ready to go through the bullets.

Here, the bullets have spread out and the obvious paths are visible.
When you are dodging, try to take notice of the spaces. There are generally 3 types of spaces:
1. bubble-bubble
2. bubble-metal fatigue bullet
3. between two metal fatigue bullets
#1 is generally the safest, and #2 can be either safe or really dangerous (say, if the 2 bullets overlap).
#3 requires some precision and make sure you LOOK AT your hitbox, cuz the trajectory of the bullet can confuse you and make you misread.
The deaths in this spell card usually are:
1. ***** misread the gap / movement mistake as you are going through and get clipped by bubble or metal fatigue bullets *****
2. did not read the gap in time and get walled as you back up to the bottom of the screen OR misread where you should've stood in the space, causing you to hit the laser as you try to move around the bullets
3. get stuck in the small triangular spaces near the bottom <-- this is usually not lethal since Remillia will be far up the screen for this to happen, so the bullets are more spread out, allowing you to have some wiggle room to get through at least the first wave most of the time (the only situation where there is a high risk of clip death is if a bubble and a very nearby - as in overlapping - metal fatigue bullet both go through the space).
The clip deaths usually happen when you are trying to dodge a dense wave (as in, all gaps are pretty risky) inside a "coffin" space. This happens
especially when Remillia moves down, causing the laser spaces to be smaller (cuz they get cut of by the bottom of screen) and the bullets to be closer together. Be ULTRA careful when you have to get through a small space and FOCUS (look at) your hitbox.
Lastly, don't be afraid to change lanes when you dodge the bubbles (i.e. say, you were dodging on the very very left side of the "space" in the laser, and then the gap is too small, you can back up and move around to the right side of the "space" instead)