is there a way to do “sub-layers” in images as we can with a typical cut file? hope i said that right.
Note at this time as you describe. You could use multiple Layers using the same image with adjusted settings for each Layer, but I’m sure you are aware of this as an option. 
I often use a typical such as Jarvis or Atkinson then fallow up with Threshhold. Maybe someday. TKS