first of all you need to have some basic understanding of the blockchain technology and have been around the technical aspect of it all to read the whitepapers and really understand them.
secondly it depends on your goals. if you are just in it for trading (an investment to make money) which is the case for most people, then reading whitepapers is a total waste of time!
So if you said read whitepaper is wasting time so what do you suggest to do before investing in project? Just jump? I dont think read whitepaper is not important. All the information about project is there so without knowledge about project, then invest in it is just like throwing money to gamble.