Skip one particular RC - HOW do I choose?

Hey,

I am targeting a 650 score. My exam is in 8-9 days and I just started doing exams to get a hint o where I will land:
GMAT official practice test 1: 500 (Q42 V18)
GMAT official practice test 2: 600 (Q45 V27)
GMAT official practice test 3: 640 (Q49 V28)

I am pretty strong in quant and reckon I will be able to get around Q50.
Entering the Verbal... I am very strong in logic, so the CR questions are a piece of cake for me. The SC questions I have a pretty hard time with, but mostly I can be able to eliminate 2-4 options so I can get the correct answer (even though it takes 90-140 seconds each time).

What I struggle with the most is the RC. For my first practice tests, i skipped all RC questions. For the second one, I skipped the last two (not mentioned to do so, but I just ran out of time). For the last one, I really did an effort to try to do all RC questions. To my surprise my score did not improve that much. So no I am thinking of what the smartest strategy for me would be. I am thinking something like this, and I would really appreciate your opinion on it.

For natural science passages, I am not understand anything. There are so many different words I am not familiar with, and I am not able to distinguish them from the core of the meaning. For practice test 3, as the first passage in the text, I got a short passage concerning natural science. I gave it a fair shot (probl. around 8 minutes) but got ALL questions wrong.

For passages concerning business, politics, society (where I am familiar with the topic), I usually can ace the questions.

Another implication is that I am a big fan of short passages. I am reading the passage carefully once to get the hang of it (takes around 3-4 minutes), then I am able to finish all the questions in around additional 2-3 minutes. With short passages, the questions have a more broader/logical score - and those suits me very well. With long passages I feel they focus more on detail stuff - that I have a more hard time dealing with.

In my head, I have this matrix of RC:
Subject/Length - Society/Business/Politics - Natural Science/Animals
Short - DREAM (100 % accuracy? - A more grey area
Long - Grey area - Dead end (0-50 % accuracy)

I think the most ideal strategy would be for me to skip at least one RC, that would give time to be more accurate on other questions, and really improve my score. Does this sound like a good idea? I think so as the option is to rush through it otherwise and still most likely get it 100 % wrong.

What I am wondering is how do choose WHAT RC to skip. If I have understood everything correctly, the questions in the beginning are far more important than those in the end (?). So I have to base my choice on that as well. What I have come up with is something like this:

First RC passage in exam: Never skip if it is part of first 0-7 questions. Otherwise skip if it is a long+natural science passage.
Second RC passage in exam: if not skipped the first passage, skip only if it is a long+natural science passage.
Third RC passage in exam: if not skipped anyone earlier, skip if it is a long+natural science passage OR natural science passage. If it is just a long passage, adjust choice after time/overall feeling
Fourth RC passage in exam: if not skipped anyone earlier, skip if it is a long+natural science passage/long passage/natural science passage. Of course, I will make this decision after evaluating my time situation.

This is the best I come up with. Any ideas?

All the best,

Gustafe