Select-color range basically just selects the darker colors, from just under 128 medium gray and down to 0 black. I don't even use the starting painted lines as they get obliterated by merging with the difference clouds. The fuzziness lets you "almost" select higher colors...it sort of says to itself, "we were asked to pick this range but we'll leave room for error". So when you hit the delete once it does what it is told and by hitting delete a second time it says to itself "good thing we were leaving room for error so we'll delete a bit more this time".
But I think the main gist of what you're asking is if the original painted white lines retain their importance for later steps...the answer is no. Could they? Sure, but I didn't think that far ahead. I was just deleting the darker colors and not worrying about original placement. I could go back and give that a test drive...it will keep the blacks in place but delete everything outside of the painted lines and the darker colors might be interesting to see how they interact with the layer styles of color overlay.