You should try the MGMAT SC book - it's a good book to solidify your SC understanding.

You said that your bad at SC and after question 5 missed every single SC question. It's clear that SC is your weakness, but doing what you have suggested (doing SC questions even faster to move on to the rest of the test) is the wrong route.

Often people will begin their studies by working on their strong points while neglecting the weak ones. However, at some point in time this will cause their scores to plateau - the questions they get wrong due to weaknesses will hold down their scores like a ball and chain.

The strategy you have suggested amplifies this by scenario - you'll be spending even less time on your weakness. SC is one of the easiest areas to make big gains so I suggest putting some effort in turn your weakness into a strength.