I advise students NOT to do what you have mentioned. It is not a good strategy to skim in this way. Instead you need to re-train yourself to look at the passage in a way that is different from most of what you read. In most cases people are reading for details. You want to know what the symptoms are of this illness that you have, you want to know the price of each one of the options on the car, you want to know the specifics of the computer you are buying.
On the GMAT it is different. The details are the very things NOT to focus on. You want to know the theory rather than the names, dates, and numbers. You want to be able to say that "some isotopes are heavier so they do not rise as easily when evaporated and therefore are more concentrated in sea water" you cannot get this from skimming.
The key is to not get caught up in the details and also to not be too worried about one or two vocabulary words. You can get every question right on a passage while still not knowing exactly what a certain word means. That is the key to reading. You are reading for the general information and not getting lost in details or vocab, but also not skimming.
Here is an article that I wrote that might help you with the proper way to think about Reading Comp.
https://www.beatthegmat.com/mba/2012/08/ ... prehension
