Trying to guess if the question is experienmental will not help.
For me, I treat each question equally. If I know the concept, then I know. If I don't, then I don't. If its taking too long, I make an educated guess and move on.
IMO, the most important questions are from Q1-15.
GMATPrep, I missed 13 questions in Quant but still got a 49, not sure how that happened.
Don't be afraid to take a flying leap of faith.. If you risk nothing, than you gain nothing...