I have been wrapping my own coils for quite awhile now. When I make a new coil for a RBA I try for .5 ohms, but they vary between .49 and .53, not a big difference, and don't notice a difference when vaping. I use TC for these coils, I let the mod figure it out. All I do is set the temp, and that varies between juices anyway.
Don't listen to Bebop. He can be a little zealous, overly dramatic and extraordinarily pompous sometimes. I know him personally and will deal with him accordingly. Just know that he holds coil builders in the highest regards and likens them to the great artisans of the past whose monuments endure the ages and awe generations.
Im sure if he were here right now he'd say something simple like " If thoust aim for .4 and thou strike .38 or .42 then thee have hit the bull's eye as surely as the archer has split the apple atop his son's head" or something like that.