Ointments during tattooing process

I'm in accelerator program. I know to use ointments while doing line work, but in some of the modules Jay doesn't use once shading, color packing? Is ointments not necessary during these portions of tattoo process? Will the ointments effect color packing, shading? Or do I still use ointment during shading, coloring? Or just wipe with Green soap soaked paper towel? Or do I just use ointments on parts that have been tattooed only, during these portions of process to keep from staining only? Any help would be great! Thank you in advance!

Reading your post, I have realised that I do exactly that, use Vaseline whilst lining but don't use it when shading or colour packing. I think it's because when lining, I don't want to wipe away the stencil, so put a light covering of Vaseline over the design. Once the outline is done the vaseline isn't required....just the way I do it, don't accept it as the norm.

That's what I figured was main reasoning was stencil wiping away. But wasn't sure if was necessary after line just as a skin protectant in general, not just over colored areas to keep from staining. Thank you so much for clarifying that for me!