it's not required to hit them at exactly the same time, I do them seperately because it's easier. Also the closer to the wall you are, the higher you'll go, if you get right next to it you'l shoot twice as high as the movie shows, but it makes it tougher to homing attack the switch obviously because of all the speed.
keep in mind it's useful for some other levels as well, particularly metal harbor to skip the pulleys.