Things will only change if you decide that rather than 1:1 macro (which is what the OP asked for) you want to fill the piece of film with the image of your object. Then you need 1:1 on 135, ~2:1 (approximately double lifesize) on 120, 4:1 on 4x5
Exactly. But, you will have to enlarge the 4x5 sheet 1/4 as much as the 35mm! So does it all cancel out? Does shooting at 4:1 then contact printing have any advantage over shooting at 1:1 and enlarging 4x?

People talk like shooting to smaller magnification and enlarging is better than shooting at larger magnification then enlarging less. At least that's the way it seems because they always advocate 35mm for macro applications and say leave the view camera at home. Landscape, it's exactly the opposite, both for supposed image quality reasons.