That's why it's got a ton of cautions!
I've done it only a half dozen times and it did work every time. Even did it on a few aluminum intakes, and while I did go slower and used air some instead of just oxygen, it worked out fine.
This is not for the guy that doesn't have a lot of experience, but some of those passages will not respond to much else.
I will say that if it's your own car and you are not under the gun to get it fixed fast, removing the intake and having it hot tanked is another option, but if you sprayjet an aluminum intake, it stil won't clean the passage, just soften it.