I think it's similar to the debate over "works vs grace".
Speaking about my practice, it seems obvious to me that a regular practice of spiritual disciplines is not just beneficial in a general sense but also does something to drive a process. But said process, once in motion, or once it becomes evident (it might have been in motion before, unnoticed), has an autonomous quality to it, as well - it happens whether I like it or not. However, with awareness of the developmental process, I have to say it is much "better" - maybe faster, maybe smoother, maybe with more clarity, hard to pin-point - to be doing the practices than not, even if the process moves on regardless.
So yeah, ...
Oh, yes, I see what you mean.
As far as I understand Gnostic mysticism, and this probably isn't something that a lot of Gnostics agree with me on, it pretty much is all about grace. If we practice at all or learn to practice, that's thanks to Autogenes (or Logos) reaching out to Sophia within us.
We're supposed to see all of our progress as coming from beyond us, and therefore not necessarily fully within our control. We are blessed with the drive for spiritual growth and the methods to attain it, and it is Autogenes that determines how smooth or dramatic our progress is.
So, in a sense, I actually agree that the practices themselves are important and can help the process along. I just don't see the practices and the progress they generate as necessarily something we control.