How to optimise robtargets rotation about their z-axes?

Hi. For my trajectory i do not need my tool to have any specific rotation about the z-axis for any robtarget, i have used the "Align Target" feature for now. However, i would like to know:

Is there a good way to make sure my manipulator reaches each target with as little unneccessary rotation of my tool as possible?
or
Is it possible to make the trajectory ignore the z-rotation completely, and go with the simplest way to reach the target direction?

To clarify, i have calculated quaternions which point the z-axis of each robtarget the way i need and that is all i need from each target, not the rotation about z.

I really hope you can help me out. Thank you!