You will need to have it down for the vertically scrolling section later in the game where you jump from rock to rock to stay from falling off the screen (Fushin magic can help a bit there too).
https://www.youtube.com/watch?v=cQDK6cwlP08
At 2:47 is the Body Weapon boss fight, as you can see no double jump required. You'll notice the guy has managed to keep his shuriken power-up from the level so the boss goes down pretty quick, same method can apply for regular shuriken, just takes a bit longer. I don't personally do it that way, I like to dive kick it in the eyeball and make it hard for myself by double jumping the hand, but whatever works. Duck if you see it charge up the particle beam, but keep some distance because it sucks you towards it as it charges. If you still have trouble, use the fire magic, but remember if you do this you lose the Ninjutsu bonus.
Speaking of the jumping dive kick, not only is it useful to kill a chain of enemies in quick succession without touching the floor, it's also great simply to get back on the ground quicker than you usually would. That's the thing with this game, the moveset is flexible enough to allow for extremely fast and aggressive play. The problem is the levels perhaps don't quite realise it's full potential.