Pass-Through engraving determined by Layer DPI or imported Image DPI?

I’ve been doing experiments with Image engraving. I’ve done a lot of my general fill engraving to high DPI (usually as high as 600). But two things occurred to me. 1.) after doing a proper DPI test based on an Imag-R file, I found that my machines DPI is roughly 242-254. Though, I just realized that this was based on Image Pass-Through and not on Fill settings. Uhg, now I have to check if Fill is DPI as well., 2.) examining the Imag-R project File, all the images are set under the same image layer in Lightburn, and that layers DPI is set to 212. Meaning the images DPI doesn’t seem to be determined by Lightburns Layer DPI setting, but rather the DPI of the Image pre-dithered.

I saw on a post here that Pass-Through = Don’t Touch.

So, does this mean that even if I had the Layers original DPI setting was set to 12, the image will still be engraved at the DPI set by the image? Should it be set back to Lightburns image layer default, being 254? Or should the DPI setting of layer be set to my Machines optimal DPI, being roughly 242-254? When I pre-dither the image rough Imag-R or Photoshop, I already have the Image DPI set to 242.

Also, Pre-processed images from Imag-R have been producing fantastic result, all be it a little on the faint/light side. If Pass-through is an option based on pre-processed images and they seem to be producing great results, why have any of the other settings like Stucki, Half-tone, Threshold, Atkinson , etc? are there special circumstances that Pass-through won’t work, or is it for those that don’t have Photoshop, Corel, or Imag-R to pre-process Dither? Lastly how much do Speed and Power affect a Pass-Through graving?